Months after the explosion on Lian Yu Oliver and the team continue to deal with the fallout of who lived and who died. Meanwhile Black Siren attacks the police station, and Oliver faces new challenges when he takes on the role of a father.
Anatoly's return to Star City complicates things for Oliver, who faces and F.B.I. investigation and stands on the edge of his identity as the Green Arrow being exposed. William faces the harsh reality of being the son of a "hero," and Dinah confronts John about his shakiness in the field.
An attack on Kord Industries leads to a rogue black ops team targeting a deadly chemical weapon, while John suffers a crisis of leadership in his new role. Meanwhile, Oliver searches for a way to help his son.
Black Siren reemerges in Star City as an assassin for hire, but the team suspects a connection between her seemingly nondescript targets. Meanwhile Alena comes to Felicity to plea for help in a terrifying plot conceived by Cayden James, the genius criminal Helix helped to free from A.R.G.U.S.
Oliver agrees to accompany Slade on a trip to Kasnia, where Slade believes his son Joe is being held prisoner. Back in Star City Vigilante returns and threatens the life of a politician, and Dinah is shocked to discover who is beneath the killer's mask.
Oliver finds himself in the crosshairs after Slade joins up with his son's criminal organization. Back in Star City Diggle turns to the criminal underground for a drug needed to treat his condition, only for Team Arrow to come up against his dealer -- called "the Dragon."
Oliver's latest political triumph is interrupted when the F.B.I. arrests him, charging him publicly with the crimes of the Green Arrow. The team tries to stop Black Siren from acquiring dangerous technology for Cayden James, and Curtis and Felicity clash over their young partnership.
After Barry and Iris's wedding is attacked by a gang of super criminals from the infamous Earth-X Oliver, Felicity, and Team Arrow join forces with Earth's mightiest heroes to discover the enemy's plan -- even if it means taking on evil versions of themselves.
Following Oliver and Felicity's wedding celebration Quentin is abducted by Laurel's doppelganger and used as leverage by Cayden James, who wants Team Arrow to steal a piece of A.R.G.U.S. technology for him. But the team begins to fracture after Oliver learns that one of them has agreed to testify against him.
With the team disbanded Oliver finds it difficult to take on the assembled forces of Cayden James on his own. A local crime lord appeals to the Green Arrow for help, and Dinah reconnects with Vince.
With the two teams trying to work independently, Cayden James takes control of the city's computer networks and unleashes a series of deadly attacks to exact revenge on Oliver -- putting William in the line of fire.
With Cayden James holding Star City hostage, Dinah pushes the team to trust Vince as an undercover operative inside the enemy's organization. Meanwhile Quentin realizes that Laurel has been following him, and tries to reach out to her.
Cayden James announces his plan to detonate a bomb that could destroy the city, and Team Arrow scrambles to find proof that Oliver has been framed for murder. While Dinah hunts Black Siren, Cayden's allies grow suspicious about his loyalty to them.
Dinah's vendetta pits the two teams against one another, as their race to find Black Siren leads to a violent confrontation -- as the city suffers a funding crisis in the wake of terrorist extortion.
Black Siren returns under the guise of Laurel Lance, hoping her public reemergence will make it harder for her enemies to take her out. Oliver learns that Roy Harper is back and being held captive by Ricardo Diaz, and Lance and Dinah call a truce when they learn that the SCPD has become corrupted.
As Thea prepares to leave Star City to start a new life with Roy, Nyssa Al Ghul returns to warn her that she is being targeted by a new renegade faction of the League of Assassins who are in search of a map hidden by Malcolm Merlyn. Meanwhile, Dinah and Travis investigate her police captain.
Oliver and Diggle's partnership is on the line when they clash over Oliver's leadership. Meanwhile Oliver confronts the SDPD chief and the district attorney about their apparent ties to Diaz, and Curtis learns that his new boyfriend is against vigilantes.
Oliver reaches a low point when he is targeted for impeachment by the City Council and isolated by those closest to him. While Oliver struggles with his personal demons, he discovers that someone has messed with his mind.
Diaz attempts to gain a seat in a national crime syndicate by offering up Star City, but must first prove himself by retrieving a witness from federal custody. Elsewhere, Felicity and Travis turn their attention back to building Helix Dynamics.
Oliver turns to Anatoly in the hopes that he can make things right with his old friend and turn him against Diaz, while Laurel confides in Quentin. Rene returns to his team ready to fight, but they soon find themselves in the middle of Diaz's new deal with the Quadrant.
As Diaz leans on the people close to him Oliver's criminal trial proceeds with little hope for a way out -- until Diggle introduces an X-factor from the past.
After his efforts to sideline Oliver fail Diaz targets the vigilantes and their loved ones, drawing the two teams back together. Lyla puts her life on the line inside SCPD headquarters, while Felicity attempts to decipher hacked data that could expose everyone on Diaz's payroll.
After Oliver negotiates a deal with the FBI the team goes after Diaz with new allies, while a desperate Diaz tries to leverage Laurel against Mayor Lance.
