Ep 12. Uprising

Oliver Queen (Stephen Amell) returns to Starling City and discovers that his sister, Thea (Willa Holland), has turned vigilante. He is also informed that the city has been taken over by crime lord Danny "Brick" Brickwell (Vinnie Jones), who has organized various gangs into an army. Meanwhile, Laurel Lance (Katie Cassidy) visits her sister Sara's grave and decides to become the new Black Canary. Oliver tries to stop Thea from fighting as a vigilante, believing that she is not ready and will only get hurt. However, Thea reveals that Malcolm Merlyn (John Barrowman) has been training her for months and she is more than capable of defending herself.

As Oliver tries to come up with a plan to take down Brick, he realizes that he needs help from everyone he has ever saved in the past. He contacts Roy Harper (Colton Haynes), who has been living out of the city to avoid being captured by the police. Roy agrees to help, but only if they can also save his friend Sin (Bex Taylor-Klaus) who has been kidnapped by Brick's army. Oliver then visits Quentin Lance (Paul Blackthorne) and convinces him to take up arms against Brick, offering his help and resources.

Diggle (David Ramsey) and Felicity (Emily Bett Rickards) return to Starling City and join Oliver's team. Meanwhile, Ray Palmer (Brandon Routh) is still trying to perfect his suit, but is constantly interrupted by Felicity who needs his help. The two bicker and argue, but there is an underlying attraction between them.

The plan to take down Brick involves various groups of people, including firefighters, police officers, and civilians. Oliver leads the charge, but is almost shot by an officer who does not recognize him. Laurel, dressed as the Black Canary, saves him and they fight off Brick's men together. Roy and Sin are also successful in their mission to save Sin's friend, and Diggle and Felicity provide the technological support needed to take down Brick's army.

In the end, Brick is defeated and all of the groups who helped Oliver celebrate their victory. However, Oliver is still grief-stricken by the fact that his sister is fighting as a vigilante. Thea, on the other hand, is thrilled to have played a role in saving the city and is determined to continue her work as a hero.

The episode ends with a surprise twist, as Malcolm Merlyn is revealed to have been working with Brick all along. Oliver is shocked and vows to stop Malcolm once and for all.