Complete story — includes the ending
When a masked thief with superhuman strength steals a centrifuge from Queen Consolidated, Central City CSI Barry Allen arrives to help with the investigation. Later, he states that he is searching for super-powered beings in the hope that he will find his mother's murderer, thereby exonerating his accused father. Oliver realizes that the thief was enhanced using the same serum for which Ivo was searching. Roy starts to help Cindy find her missing friend, a failed subject of Blood's experiments. Oliver shoots Roy in the leg to prevent him from getting further involved. Oliver tracks the thief, but is injected with an unknown toxin. In order to save Oliver's life, Felicity reveals his identity to Barry so he can help find an antidote. Meanwhile, Merlyn puts pressure on Moira to tell the truth to Thea. Moira instead contacts Ra's, who wants to kill Merlyn for breaking the League's code by destroying the Glades. As a result, Merlyn leaves. In a flashback to the island, Oliver and Shado find the Mirakuru but, when they inject it into Slade without the required sedative, his heart stops just as Ivo arrives with his men. This episode, along with "Three Ghosts", serves as a backdoor pilot to The Flash.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Arrow season 2. HTML formatting and reference markers removed. · Content license