Oliver decides that his next target is going to be someone on Digg's list: Deadshot. They set a trap for him and Digg's spy friends get involved as well. Meanwhile, Laurel's latest clients are Eric and Nancy Moore who have agreed to testify against Edward Rasmus, a financial advisor who swindled them. The night before their deposition however, they are assassinated. Laurel takes charge of their now orphaned son, Taylor, but he saw his parents killed and is now the assassins next target. Oliver steps in to stop him but in doing so fails to back up Digg and Deadshot escapes. It creates a rift and Diggs walks out. A flashback to the island show Oliver, Wilson and Shado are preparing to free Yao Fei.

The time is fast approaching for the Undertaking to occur and Malcolm Merlyn begins to tidy up the loose ends, beginning with the scientists at UNIDAC. Oliver and Digg trick Moira into telling just what the Undertaking is about. Oliver realizes that even if he manages to eliminate everyone on his father's list he has only, in his own words, eliminated the symptoms and not the disease. Felicity locates the UNIDAC device - sort of. Thea and Roy's relationship comes to head when they are unable to locate the vigilante. Walter files for divorce. Laurel and Oliver begin a new relationship. In a flashback to his time on the island, Oliver learns just what Edward Fyers' plan is.

When Frank Bertinelli is arrested, Oliver knows it's only a matter of time before his daughter, Helena, AKA The Huntress, returns to town. To make matters worse, Laurel is picked to try Frank's case, putting her right in the path of Helena. Oliver tells Sara he will handle his ex-girlfriend, but when Helena takes hostages at the courthouse, including Laurel, the Canary will stop at nothing to save her sister. When The Huntress and Canary meet, an epic battle begins. Meanwhile, Roy realizes he needs to keep Thea safe, but doesn't like the way he is forced to go about it.