Lone Gunmen

"Lone Gunman" is the third episode of season 1. It aired on October 24, 2012.

Synopsis
Oliver is shocked when someone shoots one of his targets dead. Not appreciating the help, he searches for the gunman, discovering it to be a man going under the alias of "Deadshot". He learns that Deadshot is taking out businessmen who are scheduled to bid at an auction on an energy company and Ollie's step-father, Walter, is one of the bidders. Realizing he can't do two things at once, Arrow enlists Detective Lance’s help, though his plan has serious consequences. Meanwhile, Laurel and Tommy get caught in an awkward situation with Oliver.

Recap
Oliver tracks down another millionaire from his list, but before he can get the answers he wants the man is killed by an assassin known as Deadshot. Initially, the police suspect that the vigilante, whom they refer to as "The Hood", is responsible for the murder, but the evidence begins to prove that he did not kill anyone. Oliver decides to build a new dance club above his hideout to explain where he goes at night. While comparing the competition, Oliver finds Thea, who reveals that Laurel and Tommy had been sleeping together during Oliver's absence. Laurel becomes suspicious when Oliver does not react to the news.

Meanwhile, Oliver uses the assassin's to learn his true identity, and enlists the help of Detective Lance to stop Deadshot from assassinating more of the wealthy. Oliver manages to stop Deadshot, killing him in the process, but his bodyguard Diggle is shot during the assassination attempt. Oliver is forced to reveal his true identity to John Diggle in order to save Diggle's life. In another flashback, it is revealed that the archer who attacked Oliver was actually trying to help him. Oliver understands and escapes, but is pursued by an unknown group of armed men.