Oliver, Laurel, Mia, and William travel to Russia to get the plans for a weapon capable of stopping the monitor, and Oliver faces reminders of his past with the Bratva. Meanwhile, Diggle recruits an ally to help him steal the plutonium for the weapon.

Oliver, his team, and his children, travel to Lian Yu for one last mission. They face ghosts from Oliver's past, including an old friend, and Diggle questions Lyla's decisions.