In his quest to take down Kovar, Oliver gets help from a surprising source - Talia al Ghul. However, when she reveals what she wants from him in exchange, Oliver isn't sure he can accept her help. Felicity attempts to hack the NSA to help free Diggle but when her online efforts are flagged, she faces off against an unknown adversary. Meanwhile, Curtis tells the team about a female vigilante, Tina Boland, he uncovered online who has been wreaking havoc all over the country.

Oliver faces his biggest challenge yet as mayor. Felicity continues down her dark path with Helix. After Vigilante attacks Oliver while he's acting as the mayor, Diggle leads the team in a mission to stop Vigilante once and for all.

Oliver gets closer to the truth about Prometheus. Meanwhile, Helix refuses to continue helping Felicity until she does a favor for them.

Diggle and Felicity are shocked by Oliver's decision to ask the Bratva for help in taking down Prometheus.

Oliver, Team Arrow, ARGUS and the SCPD kick off a citywide manhunt for Adrian Chase. Helix tells Felicity they have a way to find Chase but they will need something big, and illegal, from her in return.

Just as Oliver starts to get things in order, Black Siren launches another attack on the citizens of Star City.

Oliver continues his battle with Cayden James. Dinah and Oliver have a major disagreement that endangers the life of one of their own.

Cayden James discovers a secret about the Green Arrow that pushes him over the edge. Knowing everyone and everything he loves is in danger, Oliver must decide if he can do this alone or if he needs to turn to his old teammates for help. William starts to demand more of Oliver’s time.

Laurel learns about some damaging information that affects Emiko. Always looking to protect his sister, Oliver invites Laurel to help investigate, which makes Felicity happy as her friend is now working with the team. However, when things go awry, Felicity is forced to make a choice between the team and Laurel.

After the Ninth Circle delivers a major setback for Team Arrow, Diggle reluctantly reaches out to a Four-Star General of the Defense Intelligence Agency for help, despite unresolved tension from their past. Meanwhile, Oliver discovers a piece of information that he believes will turn Emiko against the Ninth Circle. Alena returns with an interesting proposal for Felicity.

Oliver finds himself in a precarious position. SCPD shows up with a warrant for Felicity.

The battle between Oliver and Emiko comes to a boiling point which brings back some familiar faces and leaves others in dire jeopardy.