Oliver tries to balance being the mayor, Green Arrow and a father to William. Anatoly returns to Star City with a deadly agenda.

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.

Slade returns and asks Oliver for help in tracking down his son. When they learn Joe has been taken hostage by mercenaries, their mission to save him gets complicated by a terrible revelation that could shatter Slade's hopes of reunion forever. Meanwhile, Vigilante reappears in Star City.

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

Diaz targets Team Arrow and their loved ones. Oliver struggles with Felicity putting herself in danger when she gets the chance to stop Diaz for good.

With a new ally on his team, Oliver engages Diaz in an epic final battle.

In order to track down Diaz from inside prison, Oliver realizes that will require aligning with an old enemy. Meanwhile, in Star City, Felicity’s attempts to root out Diaz are thwarted by Diggle, whose allegiance to ARGUS now requires him to keep civilians like her on the outs. Realizing that she can no longer rely on her old team or old methods, a clear-eyed Felicity resolves to find a new way to go after Diaz.

Still in prison, Oliver faces his biggest challenge yet. Meanwhile, Felicity gets an intriguing offer, and Diggle asks Curtis to go undercover for ARGUS.