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.

Oliver assembles a group of unlikely allies - Slade, Nyssa, Merlyn and Digger Harkness - to engage in an epic battle against Chase and his army.

Oliver deals with the fallout of the explosion on the island.

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.

As Slade continues to uncover clues about his son’s last few years, Oliver makes a big decision. Meanwhile, the Green Arrow leads the team into battle against “The Dragon,” a villain who is stealing valuable tech in Star City.