Reunited with his sister, Oliver and Thea find themselves searching through a familiar maze of catacombs. Meanwhile, John and Lyla partner on a special ops mission.

When a mysterious new Deathstroke appears in Star City, Oliver and Team Arrow insist on taking down this villain themselves. Meanwhile, reeling from the loss of one of their own, the future Team Arrow figures out a new way to try and stop JJ.

Upon learning the key to oppose The Monitor, Oliver and team return to Russia on a mission to gather the necessary materials. Connor reunites with a figure from his past.