Oliver and his team break into the Applied Sciences division of Queen Consolidated and destroy the lab so that Slade does not have access to it to mass-produce the Mirakuru. In response, Slade attacks the team at their hideout and steals an electronic "Skeleton Key", so that he can access any lab to get the equipment he needs. The team is too late and Slade successfully steals a bio-transfuser that will allow him to transfer his Mirakuru-infused blood to the convicts he freed. Oliver tracks Slade and discovers that he has kidnapped Roy and is using him to transfuse the blood. Oliver rescues Roy, and Isabel is mortally wounded in the battle. Later, Oliver reveals there is a cure for the Mirakuru, and Felicity goes to S.T.A.R. Labs to have an antidote created. Meanwhile, Laurel investigates Oliver being the Arrow, which leads her to discover that Sara is the Canary. Laurel stops her investigation when her father tells her that the Arrow's identity is irrelevant to the symbol that he represents. Laurel later blackmails her supervisor into releasing and reinstating her father. Slade's army of Mirakuru warriors gather and Slade uses his blood to heal and empower Isabel as well. In flashbacks, Oliver kills Ivo after he tells him and Sara about the Mirakuru cure.