Peter Declan has been charged with murdering his wife, and only Oliver believes he's innocent. Arrow asks Laurel to look into Declan's case. Meanwhile, Walter investigates a warehouse that Moira mysteriously bought with the company's money.

Oliver is accused of being the hooded archer and is put under house arrest. Also, he thinks back to his time on the island, where he first met Edward Fyers and Deathstroke.

A new vigilante is killing off the people that work for mob boss Frank Bertinelli.

Oliver Queen attempts to track down a mysterious copycat vigilante who is killing people on the list.

After a string of violent armored car robberies, Oliver suspects that Ted Gaynor of Black Hawk Security is the mastermind. His name is also on the list. It leads to a major disagreement with Digg as Gaynor was his training officer on his first tour of duty in Afghanistan. Digg learns that people change. Meanwhile, Tommy is hesitant at his father's attempt at reconciliation - and with good reason. Thea celebrates a birthday but has trouble with the police when she's arrested after a car accident for driving under the influence of a narcotic.

Quentin Lance's ongoing attempt to capture the vigilante is put to a halt when a recently released criminal kidnaps his daughter to get to Arrow. Meanwhile, John Diggle insists on spying on Moira Queen to learn her secrets.

The plan to kill Malcolm Merlyn goes into operation. Arrow kills one assassin who has just arrived in the city and retrieves his cellphone. It's up to Felicity to break into it and find out just who the target is. A birthday dinner for Tommy Merlyn is interrupted by his father who brings him a present. Tommy makes it clear that he is not welcome and does not want a relationship with him. Malcolm is to receive an award at a civic gala and after a heart to heart with Oliver, Tommy decides to attend. When Oliver learns that Malcolm is the target, he races to save Tommy. Once the attack begins, Malcolm and Tommy takes refuge in his office and Malcolm is about to reveal that he is the Dark Arrow but is seriously wounded before he can do so. Arrow arrives on the scene and to convince Tommy that he is there to help, reveals his identity.

After a major fire, Oliver decides it's time to eliminate real estate developer and slumlord John Nicol, another person on his father's list. He's beaten to the punch when another vigilante, The Savior, who kidnaps Nicol and ultimately executes him - broadcasting the whole thing over the Internet. The new vigilante is identified as a man whose wife was killed in a bodega robbery in the Glades district. When he kidnaps Thea's new boyfriend, Roy Harper, Oliver decides to stop him. Meanwhile, Laurel is upset to find that her father has come around to her mother's belief that her sister may still be alive. In a flashback to his days on the island, Oliver learns why Yao Fei refused to leave.

Vertigo is again appearing on the market even though The Count, who created the drug, is still in a psychiatric hospital. Soon after Oliver confirms that he's still there, he somehow manages to escape. The Count's psychiatrist says his patient overpowered him and has concluded that his insanity was just a ruse. The police suspect Tommy may be dealing drugs from the club and Det. Lance gets a search warrant. Oliver is not sure what to believe and Tommy, feeling his onetime friend has no respect for him, quits. He turns to his father for a job. Digg gives information about Deadshot to a former intelligence colleague. On the island meanwhile, Oliver begins to learn how to use a bow.

After taking a mob accountant's laptop, Oliver plans to return the money to its rightful owners. Felicity however finds that Dominic Alonzo - the operator of an illegal casino and the head of a gang known for kidnapping - was paid $2 million to kidnap Walter. Arrow pays him a visit and is told that Walter is dead. He tells his mother and Thea but Moira rushes to Malcolm Merlyn demanding to know why he broke their agreement. He assures her that Walter is alive and will be released as long as she continues to cooperate. Oliver is listening to the entire conversation and now knows that his mother is involved, just as Digg had warned him. Flashbacks reveal Malcolm's plan and also the the sinking of Robert Queen's luxury yacht was no accident. Laurel meanwhile tries to make up with Tommy and finally learns the real reason he broke up with her.

The time is fast approaching for the Undertaking to occur and Malcolm Merlyn begins to tidy up the loose ends, beginning with the scientists at UNIDAC. Oliver and Digg trick Moira into telling just what the Undertaking is about. Oliver realizes that even if he manages to eliminate everyone on his father's list he has only, in his own words, eliminated the symptoms and not the disease. Felicity locates the UNIDAC device - sort of. Thea and Roy's relationship comes to head when they are unable to locate the vigilante. Walter files for divorce. Laurel and Oliver begin a new relationship. In a flashback to his time on the island, Oliver learns just what Edward Fyers' plan is.

Oliver awakens to find himself Malcolm Merlyn's prisoner. He manages to escape and away with help from Digg. Malcolm accelerates his timetable as a result. Felicity is questioned by Det. Lance about her hacking activities but is interrupted by Oliver who tells him about Malcolm's plan to destroy the Glades. Tommy confronts Oliver about Laurel but refuses to believe that his father is up to no good. Malcolm comes clean about his plans and Tommy realizes that his father is insane. Moira goes public with what she knows, urging the residents of the Glades to evacuate. Roy and Thea get caught up in the mayhem. While Oliver and Digg go after Malcolm, Felicity tries to neutralize the device via Lance. Malcolm has planned it all very well, however. In a flashback to his time on the island, Fyers attempts to bring down an airliner.

Oliver is concerned when a mysterious illness sweeps the city, infecting hundreds of people, including Diggle. Oliver discovers Vertigo in Diggle's blood and realizes The Count has broken out of prison and is once again distributing his drug. Meanwhile, Moira goes on trial for her participation in the Undertaking. ADA Adam Donner collapses in court with Vertigo symptoms so Laurel must step in and try the case against Moira. Oliver is torn between standing by his family during the trial and catching The Count. However, things change when Felicity follows a lead and walks straight into a trap set by The Count.

After an impossible break in at Queen Consolidated, CSI Barry Allen comes to Starling to help with the investigation, Sin asks Roy for help so Thea tags along.

Oliver rallies his team as Slade's soldiers attack the city. Felicity gets a call from S.T.A.R. Labs with game-changing news and Thea comes face-to-face with her father.

As Oliver's face off with Slade escalates, his resolve to the no-kill rule is tested. Especially as Slade targets the woman Oliver loves.

As a new enemy emerges seven months after Slade's attack upon Starling City, Oliver battles with the help of his teammate Roy. However, with the Arrow's presence elsewhere someone he had loved dearly is hurt.

Team Arrow is in pursuit of a new villain who poses a threat to Starling City. Meanwhile, Oliver is worried about not having heard from Thea.

Oliver, Roy and Diggle fly to Corto Maltese to find and convince Thea to come back home to Starling City, Lyla sees this as an opportunity and asks Diggle to locate an A.R.G.U.S. field operatives there.

Nyssa and Oliver join forces to go after the Dark Archer.

Felicity's family and backstory come to the fore. Felicity tries to find common ground with her mother but it is clear the two are very different.

Ted Grant becomes the primary suspect when a body is found in the Wildcat gym and Roy shares a secret with Felicity.

Oliver must stop an Arrow-obsessed serial killer, Carrie Cutter, who is convinced that The Arrow is her one true love and will stop at nothing to get his attention. Unfortunately, her way of getting his attention is to kill people. Meanwhile, Ray asks Felicity to be his date for a work dinner with important clients. Thea auditions new DJs for Verdant and meets Chase, a brash DJ with whom she immediately clashes.

As Oliver, Arsenal, and Diggle pursue a killer named Digger Harkness, they encounter an ARGUS team; Oliver and the Flash team up to try and stop Harkness.

The League of Assassins give Oliver 48 hours to find Sara's killer, or Starling City citizens will die. Oliver then has an epic confrontation with Ra's al Ghul.

The Team's worst fears are realized when Merlyn informs them of Oliver's death. Meanwhile Ray Palmer tests part of his ATOM suit out and Laurel Lance decides to pursue justice outside of the law by taking up the mantle of the Black Canary.

Arsenal and Diggle confront Laurel about trying to step into her sister's shoes and warn her to stop before she gets herself killed. However, the villan Brick kidnaps the city's Aldermen and threatens to kill them all unless the police evacuate The Glades, it's all suits on deck. Meanwhile, Ray steps in to help Lance and the police force fight Brick, showing Felicity a new side of her boss. Malcom tells them that Ra's al Ghul is after his family and they must leave town immediately.

Still operating without Oliver and desperate to stop Brick, Team Arrow is forced to consider Malcolm's offer to help shut Brick down as Malcolm has a personal score to settle with the felon. Roy and Laurel point out that the team could use some help to save the innocents of The Glades, but Felicity is adamantly against it. They look to Diggle to make the final decision. Meanwhile, the flashbacks chronicle Malcolm's descent from kind-hearted father and husband to cold-blooded killer after the murder of his wife.

Oliver struggles to adjust to the changes that have taken place within Team Arrow; Laurel ignores Oliver and pursues Vertigo - who injects her with the drug; Thea receives a surprise visitor.

Malcolm puts Oliver and Thea in a dangerous situation that lands them on Lian Yu with Oliver's former enemy, Deathstroke. A flashback reveals when Oliver and Maseo returned to Starling City to retrieve the Omega bio weapon, and despite being under strict orders from Amanda Waller not to reveal himself to anyone, Oliver looks in on his family, Laurel and Tommy.

Malcolm is captured by Ra's al Ghul and taken to Nanda Parbat. Because of his love for Thea, Oliver considers saving Merlyn. Ray is obsessed with finishing his Atom suit so he can save the city but Felicity fears he is heading down the same path as Oliver and tries to pull him out of the lab.

Oliver thinks about the offer Ra's Al Ghul gave him, but to do so theres a catch.

It's celebration time as Diggle and Lyla get married. However, Deadshot interrupts their honeymoon and tells them the Suicide Squad has been given a new mission - rescue United States Senator Joseph Cray from a hostage situation in the Republic of Kasnia. Amanda Waller breaks down the mission and introduces them to the newest member of the Suicide Squad, Cupid. Meanwhile, Oliver learns about Ray's new Atom costume and the two have a heated stand-off. Felicity and Ray hit a rough patch.

During an attack on the mayor's office, Ray is critically injured. Felicity is pleasantly surprised when her mother, Donna Smoak, shows up at the hospital to offer her support. With the SCPD out in full force looking for the assailant, Oliver and his team work hard to stay one step ahead of the police to find the man responsible. However, things come to a head when Ra's al Ghul kidnaps Captain Lance.

Lance continues his mission to take down the Arrow. When a meta-human named Jake Simmons, who kills people with blasts of energy and plasma, starts terrorizing Starling City, Oliver is forced to ask Ray for help.

Ra's al Ghul finally makes Oliver an offer he can't refuse. The team joins Oliver on his journey to Nanda Parbat where a heartbroken Felicity decides to take matters into her own hands.

Oliver goes through a transformation; Laurel asks Felicity and Diggle to help Nyssa face the League of Assassins.

Oliver must complete two final tasks before becoming the next Ra's al Ghul; Nyssa is threatened; Malcolm makes an offer to the team; Thea visits Roy.

Ra's al Ghul sets his plan in motion, putting everyone in danger; Oliver must decide if he is strong enough to handle his new role - and what it will mean for his team and his soul.

A new enemy lures Oliver Queen back to Starling City and forces him to put on the hood once more.

Oliver and Thea are concerned when a family friend plans to run for mayor; Thea starts to exhibit side effects from the Lazarus Pit; Felicity asks an employee for help with a business decision.

The growing tension between Oliver and Diggle puts both their lives at risk when they go after Damien Darhk and a H.I.V.E. deployed meta-human. Meanwhile, Laurel talks Thea into returning to Nanda Parbat to ask her father to put Sara into the Lazarus Pit. However, Laurel is surprised when Nyssa refuses to do it.

Laurel must deal with the repercussions of taking Sara to Nanda Parbat. Meanwhile, Oliver asks Captain Lance for a favor and while he's not surprised at the response, he is surprised at what he finds out next.

Oliver calls in a favor from old friend John Constantine when Sara takes a turn for the worse.

Felicity is frantic when she learns that Ray is alive and being held by Damien Darhk. Felicity's guilt over not finding Ray sooner causes tension between her and Oliver.

A shocking revelation complicates the battle between Team Arrow and Damien Darhk; Thea loses control in front of Alex.

Oliver and Barry hide Kendra and Carter in a remote location while they try to figure out how to defeat Vandal Savage; Felicity, Thea, Diggle and Laurel work to come up with a weapon to destroy Vandal.

Oliver moves against HIVE; Malcolm goes to see Thea, leaving her with a warning; Damien Darhk retaliates at Oliver's holiday party.

Oliver must deal with the devastating consequences of Darhk's last attack. Seeking revenge, Oliver goes on a brutal manhunt looking for Dahrk.

An agent of Shadowspire who was an enemy from Diggle and Andy's wartime past shows up to Star City. Diggle must learn to trust Andy but he got more than he wanted about their shared time from war. Oliver however must learn a new way of life when Felicity is now in a wheelchair and receives her codename.

The team faces off against a formidable villain nicknamed The Calculator (guest star Tom Amandes). Meanwhile, Nyssa (guest star Katrina Law) makes her move and Roy Harper (guest star Colton Haynes) returns to Star City.

Oliver receives an offer from Nyssa that is hard to refuse, Meanwhile Thea continues to battle the bloodlust Malcolm steps in to help his daughter, and Laurel has a Heart to Heart talk with Nyssa.

Team Arrow uncovers HIVE's plan to take them out for good, leading Lance to wonder if Donna is better off without him and Oliver to consider telling Felicity about his son.

Oliver calls in his old friend Vixen for help in fighting Darhk, while Thea has a heart-to-heart talk with Malcolm.

Following the events of William's kidnapping, Darhk has become less powerful, but Carrie Cutter, a.k.a. Cupid, has emerged into Star City to cause chaos on the city and the Green Arrow.

The Bug-Eyed Bandit escapes from jail and turns up at Palmer Tech threatening to kill everyone in the building unless she gets the bio-chip that was implanted in Felicity's spine.

Oliver and Diggle find out Merlyn wants to break Darhk out of prison; Laurel gets a surprise offer.

Oliver and the team struggle to come to terms with a friend's death, especially Diggle, who is overwhelmed with guilt for choosing to believe Andy had changed.

As Oliver and Felicity look for a magical solution to defeat Darhk, a vengeance-driven Diggle gets a lead on Andy's whereabouts and heads off to confront his brother. Meanwhile, Alex takes Thea on a vacation that quickly turns into a nightmare.

When Team Arrow learns what Damien Darhk's next move is, Felicity realizes she needs to ask her father, Noah Kuttler, for help. Noah and Oliver have a heart to heart talk that leaves Oliver rattled.

Following the shocking events in the previous episode, Oliver and Diggle race to rescue Thea, while Felicity, Curtis and Noah join together to stop Darhk.

Oliver teams up with a surprising force in an attempt to stop Damien Darhk and his magic once and for all.

Oliver wakes up to a life in which his parents are alive and he is about to marry Laurel; Felicity faces a new threat with the help of The Flash and Supergirl.

Prometheus goes to extreme lengths to destroy Oliver. In flashbacks, Oliver's violent tendencies come to a head in a confrontation with Anatoly.

Black Siren returns to give Chase help; Felicity plans a birthday party for Oliver; Lance is angry with Rene for missing the custody hearing about his daughter.

Oliver assembles a group of unlikely allies - Slade, Nyssa, Merlyn and Digger Harkness - to engage in an epic battle against Chase and his army.

Nyssa al Ghul returns to Star City to let Thea know that a group of renegade League of Assassins members are planning to attack her.

Still trapped in each other's bodies, Oliver and Barry head to Gotham City with Supergirl to find out why their reality changed and cross paths with the mysterious Kate Kane.

In the wake of discovering what his future holds, Oliver will find himself pit against his most challenging battle yet, one that will leave the multiverse hanging in the balance.

Still operating without Oliver and desperate to stop Brick, Team Arrow is forced to consider Malcolm's offer to help shut Brick down as Malcolm has a personal score to settle with the felon. Roy and Laurel point out that the team could use some help to save the innocents of The Glades, but Felicity is adamantly against it. They look to Diggle to make the final decision. Meanwhile, the flashbacks chronicle Malcolm's descent from kind-hearted father and husband to cold-blooded killer after the murder of his wife.

Nyssa and Oliver join forces to go after the Dark Archer.

Oliver moves against HIVE; Malcolm goes to see Thea, leaving her with a warning; Damien Darhk retaliates at Oliver's holiday party.

Oliver rallies his team as Slade's soldiers attack the city. Felicity gets a call from S.T.A.R. Labs with game-changing news and Thea comes face-to-face with her father.

Oliver is concerned when a mysterious illness sweeps the city, infecting hundreds of people, including Diggle. Oliver discovers Vertigo in Diggle's blood and realizes The Count has broken out of prison and is once again distributing his drug. Meanwhile, Moira goes on trial for her participation in the Undertaking. ADA Adam Donner collapses in court with Vertigo symptoms so Laurel must step in and try the case against Moira. Oliver is torn between standing by his family during the trial and catching The Count. However, things change when Felicity follows a lead and walks straight into a trap set by The Count.

Oliver receives an offer from Nyssa that is hard to refuse, Meanwhile Thea continues to battle the bloodlust Malcolm steps in to help his daughter, and Laurel has a Heart to Heart talk with Nyssa.

Black Siren returns to give Chase help; Felicity plans a birthday party for Oliver; Lance is angry with Rene for missing the custody hearing about his daughter.

Oliver and Barry hide Kendra and Carter in a remote location while they try to figure out how to defeat Vandal Savage; Felicity, Thea, Diggle and Laurel work to come up with a weapon to destroy Vandal.

Oliver must complete two final tasks before becoming the next Ra's al Ghul; Nyssa is threatened; Malcolm makes an offer to the team; Thea visits Roy.

The plan to kill Malcolm Merlyn goes into operation. Arrow kills one assassin who has just arrived in the city and retrieves his cellphone. It's up to Felicity to break into it and find out just who the target is. A birthday dinner for Tommy Merlyn is interrupted by his father who brings him a present. Tommy makes it clear that he is not welcome and does not want a relationship with him. Malcolm is to receive an award at a civic gala and after a heart to heart with Oliver, Tommy decides to attend. When Oliver learns that Malcolm is the target, he races to save Tommy. Once the attack begins, Malcolm and Tommy takes refuge in his office and Malcolm is about to reveal that he is the Dark Arrow but is seriously wounded before he can do so. Arrow arrives on the scene and to convince Tommy that he is there to help, reveals his identity.