Billionaire playboy, Oliver Queen, has been considered dead for five years. Now, he has returned. But something, during those five years, has changed him into a mysterious green hooded archer.

A mysterious sniper called Deadshot is taking out bidders at an auction for an industry company. The bidders include Oliver's stepfather, Walter Steele.

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's next target is Scott Morgan, a power executive who jacks up prices for electricity when people most need it. John Diggle suggests they go after the gang of bank robbers that recently wounded a police officer during a daytime heist. Oliver is not so keen but John isn't the kind of guy who gives up very easily. Oliver quickly identifies one of them as a high school acquaintance, Derek Reston - and learns that Reston may have turned to crime because of something Oliver's father did. Tommy meanwhile isn't having much luck with his hoped for romance with Laurel. He seeks Thea's advice. Flashbacks show Oliver's doubts about his survival on the island.

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

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.

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.

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.

When a dangerous criminal from Lance's past (MICHAEL EKLUND) escapes from prison, Felicity offers herself up as bait so Arrow, Diggle and Lance can capture him...but plans go awry.

After a fight with Cyrus Gold, aka the Acolyte, Oliver is drugged and left for dead. Determined to cure him, Felicity makes a risky decision. The cure causes Oliver to hallucinate, and what he sees forces him to confront his past. Meanwhile, Barry Allen continues to help Felicity, and their connection grows stronger. The Arrow asks Quentin to look into Gold, but when the stakeout on Gold goes bad, someone is killed. Roy is captured and tortured by Brother Blood.

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.