Oliver encounters a mysterious woman, Helena Bertinelli, daughter of mob boss Frank Bertinelli, who he can finally be himself with, but he soon comes to realize she's hiding dangerous secrets of her own. Helena is on her own personal mission of vengeance and Oliver is caught in the middle. Meanwhile, Tommy is blindsided by an unfortunate turn of events and turns to Laurel for support.

As Oliver and Helena grow closer, Oliver trains her to be his ally, complete with showing her how to use a crossbow. Diggle disapproves of Oliver sharing his secret with Helena as he's not sure she can be trusted, but Oliver refuses to listen to his concerns. Helena's quest for revenge proves to be too strong for Oliver to handle after she kills the head of the Triad and all hell breaks loose.

Oliver discovers that after he and his father went missing, Moira and Thea stopped celebrating Christmas. Determined to make up for lost time and restore a sense of normalcy to the Queen household, Oliver decides to throw the family a Christmas party. Meanwhile, Tommy asks Laurel to spend Christmas with him but she points out that Christmas was also her sister Sara's birthday and she needs to be with her father. Tommy suggests changing things up might be the best way for everyone to heal but Laurel isn't sure her father is ready for that. Meanwhile, Diggle tells Oliver someone is murdering the people on his father's list with arrows, which sends Oliver off to face his toughest adversary yet.

Oliver’s confidence is shaken after being beaten by the Dark Archer and he takes a break from being Arrow. However, when Laurel calls Arrow for help investigating a firefighter’s suspicious death, he reluctantly agrees but his hesitance while fighting almost costs him his life. Meanwhile, Tommy throws a benefit for the firefighters and Thea tries to lift Moira out of her depressive state.

The next person on Arrow's list is Diggle's commanding officer and mentor from Afghanistan, Ted Gaynor. Oliver suspects Ted is responsible for recent armoured truck robberies, but Diggle defends Ted and takes a job at Ted's security company to keep an eye on him. Oliver decides to make a move on Ted, which puts him at odds with Diggle. Meanwhile, Thea suspects that Moira is having an affair with Malcom. Tommy and Laurel have an awkward dinner with Malcom.

Thea is in trouble with the police after she gets caught using a drug called "Vertigo." Oliver thinks the only way to keep her out of jail is to find the dealer, a man who goes by the name of "The Count". Oliver turns to McKenna Hall, an old flame and current Vice cop, for help. Meanwhile, Laurel steps in to defend Thea, and Felicity gives Oliver some disturbing news about Moira.

Cyrus Vanch, a nefarious criminal, is recently released from prison and intends to re-secure his position as leader of the underworld. His first step is to take down his biggest opponent in the city - Arrow. Meanwhile, Oliver shows Moira his father's notebook and questions her about the names on the list. Thea is miserable as she starts her internship with Laurel at the legal aid office and Detective Lance makes a deadly mistake that puts Laurel in the crosshairs of Vanch.

After Oliver is shot, he turns to a surprising person for help - Felicity. Diggle is stunned when he sees Felicity walk through the front door of the lair dragging a dying Oliver behind her, and the two team up to save Oliver's life. As Oliver hovers between life and death, he flashes back to a seminal event on the island - a daring escape attempt with his new friend Slade Wilson.

Felicity tells Oliver he's all work and no play, so he asks Detective McKenna on a date. A jewel thief named Dodger hits Starling City and targets someone very close to Oliver. Meanwhile, while working with Laurel, Thea gets her purse stolen by a very fast pickpocket named Roy Harper. Moira makes a move against Malcom.

Oliver and Diggle learn that Deadshot is still alive and his next target is Malcom. Malcom invites Tommy to attend a benefit honoring Malcom for his work with Starling City but Tommy refuses to attend. Oliver encourages his friend to mend his relationship with his father while he can. Meanwhile, Oliver struggles to balance his new relationship with McKenna and his duties as Arrow.

With his nightclub set to open and a new romance brewing with McKenna, Oliver is as happy as he's been since returning to Starling City. But when Oliver's ex, The Huntress, suddenly returns to town, she threatens to destroy everything and everyone he cares about. Meanwhile, Laurel and her father struggle with the return of Dinah Lance who claims she has proof Sara is still alive. Thea gets Roy Harper a job at Oliver's club, but he's not too inclined to stop his life of crime. Oliver and Tommy are thrilled they were able to get Steve Aoki to play at the opening of their new nightclub, Verdant.

An angry resident of The Glades who calls himself "The Savior" embarks on a kidnapping and killing spree to punish those he believes have wronged the residents of his neighborhood. To make things worse, he broadcasts these murders online and claims he was inspired by Arrow's vigilantism. Oliver is horrified by this statement and vows to stop "The Savior," but his manhunt in intensified after Thea comes to him in tears and tells him Roy has been kidnapped. Laurel is surprised when her father starts to believe her mother's claim that Sara is still alive. Meanwhile, Malcom tells Moira to find the person responsible for his attempted murder.

When a young woman meets a violent death after partying at Verdant, Detective Lance and his new partner, Detective Hilton inform Oliver and Tommy that she was on the drug Vertigo. Oliver immediately pays a visit to the mental institution where The Count is locked up, but finds he is in no condition to deal drugs. However, when The Count escapes and Starling City is flooded with even more Vertigo-related violence, Oliver and Diggle make it their mission to track him down. After Detective Lance uncovers incriminating evidence against him, Tommy goes to great lengths to clear his name, and the fallout from his actions leads Tommy down a new, unexpected path. In a flashback to the island, Oliver recalls the lessons he learned from Slade and Shado.

Deadshot returns to Starling City after taking down a U.S. Ambassador and six others overseas. By keeping tabs on A.R.G.U.S.'s manhunt for the assassin, Oliver, Diggle, and Felicity learn that a sting operation is underway to capture Deadshot - alive. Diggle is determined to see his brother's killer dead, with or without Ollie's help. Meanwhile, Laurel takes drastic steps to protect a young witness, exacerbating friction between Tommy and Oliver. Later, Roy Harperunconventionally pursues all leads to find his new hero, but runs afoul of Detective Lance. Back on the island, Oliver recalls how Shado helped him incrementally gain confidence with a bow and hit the target for the first time.

Finding it difficult to mend fences with Tommy and Diggle, Oliver instead focuses on crossing another name off the list. While digging through a crooked accountant's laptop, Felicity discovers a transaction that could help Oliver find Walter. To reconfirm the lead, Oliver gambles that Felicity can be counted on in the field for the first time. In a flashback, Malcolm reveals to Robert Queen and Frank Chen painful details surrounding his wife's murder, and how that shaped his plans for the Glades. Meanwhile, Tommy stuns Laurel with the truth.

With the Undertaking days away, Malcolm dons his black hood to conclude business with seismologist Dr. Brion Markov and his team. Oliver and Moira entertain a number of surprise - and mostly unwelcome - visitors. Hooded confrontations at home and the Meryln Global Group reveal dark secrets. Meanwhile, Roy and Thea are still looking out for a hero. Laurel makes a decision after Tommy's revelation. In a flashback to the island, Oliver, Slade and Shado struggle to prevent Fyers from shooting a Ferris Air jet out of the sky. Paul Blackthorne and David Ramsey also star.

Oliver and Diggle race to stop the Dark Archer from unleashing his vengeance on The Glades. However, they run into a roadblock after Detective Lance picks up Felicity for questioning. Tommy and Oliver's already tumultuous relationship takes a turn for the worse after Oliver makes a confession about Laurel. After hearing of the danger in The Glades, Thea races to find Roy, inadvertently putting herself directly in the line of fire for Malcolm's devious plan. On the island, Oliver, Slade and Shado are locked in a life-or-death struggle against Fyers as his missiles lock on a full Ferris Air jetliner.