With Star City in chaos following the arrival of the villain Damien Darhk, Thea and Laurel interrupt Oliver and Felicity's new suburban life to ask for help. But Oliver soon discovers that Darhk is no ordinary criminal. In the past, Oliver is caught up in an uncertain mission after an encounter with Amanda Waller.
An old Queen family friend declares her candidacy for Mayor and immediately finds herself the target of an anarchist working with Damien Darhk. Oliver confronts Thea about her over-the-top behavior, and Felicity faces a cold reality when she returns to work as head of Palmer Technologies.
After Felicity pushes Oliver and Diggle to bury the hatchet, the two find themselves up against a meta-human in the employ of Damien Darhk and H.I.V.E. Laurel and Thea arrive in Nanda Parbat in hopes of convincing Malcolm Merlyn to put Sara into the Lazarus Pit.
Oliver goes to Captain Lance for help after discovering that a group of corrupt cops are stealing drugs and leaving bodies in their wake. While Oliver plans to announce his mayoral run, Laurel deals with the consequences of her sister's return.
Oliver must stop Sara when he learns that she is alive and attacking young women in Star City, hunting for the person who killed her. In the past, Oliver finds himself tagging along with the mystic John Constantine as he searches the island for a hidden object.
Felicity pushes herself to the breaking point after discovering that Ray Palmer is alive and being held captive, even calling into question her relationship with Oliver. Sara joins the team on the rescue mission and discovers her bloodlust, and in the past Oliver is tasked with leading an excavation mission.
Oliver and the team plot to extract Andrew Diggle from H.I.V.E.'s operation, despite John's objections. Thea loses control in front of Alex after her bloodlust returns, and Oliver takes his stand against Damien Darhk into the light of day.
Oliver and the Flash take Kendra and her new old friend Carter Hall to a remote location to hide from the man hunting them, while Malcolm Merlyn tries to negotiate with Vandal Savage directly. When Oliver learns that he may be a father, his decision changes the course of the future.
After an attack on a volunteer event Oliver's team decides to expose Damien Darhk and H.I.V.E. to the public, provoking a brutal retaliation at Oliver's mayoral holiday party. In the past, Oliver leads Taiana on a mission to recover a lost item from the Amazo.
While doctors try to save the life of someone close to him, a vengeful Oliver goes on a brutal manhunt to find Damien Darhk. After Lonnie Machin resurfaces with a similar goal, Oliver uses him to track his quarry.
An attack on an A.R.G.U.S. operative leads Diggle and Lyla to Shadowspire, a shadow organization to which Diggle's brother Andy has ties. Felicity's recovery has a bumpy start when she begins hallucinating her younger self.
The team learns that the man behind a string of tech thefts is none other than Roy Harper, who is being used by a genius villain who calls himself the Calculator. Meanwhile Oliver considers asking Darhk for help when Thea takes a turn for the worse, and Nyssa escapes from Nanda Parbat.
Holding the secret to saving Thea's life, Nyssa tries to force Oliver to hand over Malcolm Merlyn and leadership of the League of Assassins. Meanwhile, Felicity learns that her long-absent father is a high-powered criminal.
The team faces a H.I.V.E. demolition squad after they demolish a building to try and kill Detective Lance, prompting him to push Donna away to keep her safe. Meanwhile Oliver prepares for the mayoral debate, and Thea discovers the secret he is keeping from Felicity.
Needing a new game plan to counter Darhk's magic, Oliver calls upon Mari McCabe -- a.k.a. Vixen, a vigilante from Detroit -- to help free his son. Felicity learns Oliver's secret, and Thea confronts Malcolm about his betrayal.
A heartbroken Cupid returns to Star City and starts killing high-profile couples in love, prompting Oliver and Felicity to stage their own wedding to draw her out. Meanwhile Laurel must find someone to put Darhk away when his trial does not go as planned.
Bee drone maven Brie Larvan escapes from prison and comes after Felicity, demanding the cutting-edge chip that is implanted in her spine and putting Palmer Tech on lockdown. Team Arrow gets help from a new ally in their efforts to rescue Felicity, Thea, and Donna from the building.
Oliver and Diggle find themselves at odds when Oliver suspects that Andy is still working for Darhk. Laurel gets a job offer from a surprising source, and Meryln attempts to help the enemy escape from prison.
As the team struggles to come to terms with the loss of one of their own, Oliver searches for a woman who has stolen the Canary's sonic device and is using it for her own ends.
After Oliver and Felicity head out of town to learn how to stand up to Darhk's magic, Diggle takes the fight against H.I.V.E. into his own hands -- only to find himself taken captive by his brother Andy. Thea begins to suspect that her vacation with Alex is not entirely what it appears.
After learning that Darhk is plotting nuclear annihilation Felicity teams up with her hacker father, "The Calculator," for help. Thea realizes that she is a fly in the ointment of Darhk's survival colony, which has been infiltrated by Anarchy.
Oliver and Diggle infiltrate Damien Darhk's underground "ark" to rescue Thea, who has been drugged and turned against them -- while Lonnie Machin goes after Darhk and Ruvé. Felicity and her father race to secure A.R.G.U.S.'s nuclear command system, while Donna struggles with her ex's presence in Felicity's life.
All hope seems lost as a nuclear missile strike looms over the entire planet, as Oliver considers what must be done -- and what kind of man he must be -- to stop Damien Darhk once and for all.
