The growing tension between Oliver and Diggle puts both their lives at risk when they go after Damien Darhk and a H.I.V.E. deployed meta-human. Meanwhile, Laurel talks Thea into returning to Nanda Parbat to ask her father to put Sara into the Lazarus Pit. However, Laurel is surprised when Nyssa refuses to do it.

Team Green Arrow's ongoing battle with Damien Darhk is complicated by a shocking revelation. Thea's bloodlust returns and she loses control in front of Alex.

The team faces off against a formidable villain nicknamed The Calculator. Meanwhile, Nyssa makes her move and Roy Harper returns to Star City.

When Team Arrow learns what Damien Darhk's next move is Felicity realizes she needs to ask her father, Noah Kuttler, for help. Noah and Oliver have a heart to heart talk that leaves Oliver rattled.

Oliver recruits Curtis, Wild Dog and Evelyn Sharp for his team, but his training methods prove to be too much for some to handle. In flashbacks, Oliver continues his initiation into the Bratva.

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, 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.

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.

A rogue black ops team led by Onyx breaks into Kord Industries and steals something lethal. Oliver struggles to connect with William so he reaches out to a surprising source for help.

Oliver celebrates Thanksgiving with his family but the happy moment is interrupted. Meanwhile, Black Siren returns to wreak havoc on the holiday.

Cayden James ups the ante by launching his plan to take control of every aspect of the city. Despite the scope of Cayden’s plan, Oliver is determined to foil it with just the Original Team Arrow – and without the aid of Rene, Dinah, or Curtis. But things get complicated when William is endangered as a result of Cayden’s handiwork.

In his darkest place yet, Oliver wonders if he has failed at everything – being a father, a mayor and a hero. His frustration rising, Oliver lashes out at Felicity and William. A surprising visit from an old friend has Oliver questioning his next move.