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 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.

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.

After Thea gets in trouble with the police, Oliver turns to an old flame - now a vice cop - to help track down the creator of a new designer drug with lethal after-effects.

Oliver's heavy-handed approach to getting information from his mother backfires and she manages to shoot him in the shoulder. He turns to Felicity Smoak for help getting back to his hideaway. She and Digg do their best to nurse him back to health. Flashbacks to Oliver's time on the island reveals an early attempt to escape. Oliver's loyalties however prevent him from taking advantage of the situation. The reason for Yao Fei's betrayal is revealed.

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.

Oliver decides that his next target is going to be someone on Digg's list: Deadshot. They set a trap for him and Digg's spy friends get involved as well. Meanwhile, Laurel's latest clients are Eric and Nancy Moore who have agreed to testify against Edward Rasmus, a financial advisor who swindled them. The night before their deposition however, they are assassinated. Laurel takes charge of their now orphaned son, Taylor, but he saw his parents killed and is now the assassins next target. Oliver steps in to stop him but in doing so fails to back up Digg and Deadshot escapes. It creates a rift and Diggs walks out. A flashback to the island show Oliver, Wilson and Shado are preparing to free Yao Fei.

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.

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's mission takes him to Lian Yu where he tries to ignore the repercussions of the looming Crisis until he receives help from an old friend. Meanwhile, a united Team Arrow faces a recognizable villain.