Nyssa warns Oliver that he has made a serious enemy in the League before leaving and reporting back to Ra's. In flashbacks, Oliver completes his first assassination, and learns that Waller was behind Edward Fyers' actions on the island; and her intention was to kill Chien on a flight to Hong Kong.
Since Oliver stopped the attack, Waller demands him to help her find out the reason of Chien's presence.
To save Tommy, Oliver pretends to kidnap him and tricks him into thinking that it was a ruse to gain ransom money before Maseo, posing as a police officer, rescues Tommy. While he waits to convince her, Oliver assists Diggle on a mission for A. In flashbacks to six months prior, Merlyn begins training Thea to calm her mind and heal her emotional pain, while also mastering control over physical pain.
With no more leads in Sara's murder, Oliver focuses his attention on bringing Thea home. Oliver informs Nyssa that Sara was killed; and Nyssa reveals to Oliver that Merlyn is alive and Sara was sent by the League to confirm his existence.
After tracking Merlyn, Oliver agrees to meet him in a public location, where Merlyn tells Oliver that he did not kill her, but only returned to Starling City to save Thea.
Nyssa kidnaps Thea in an attempt to draw out Merlyn, known by the League as the "Magician"; but Oliver arrives to rescue Thea.
Meanwhile, businessman Ray Palmer successfully acquires Queen Consolidated under a plan of rebuilding the city and renaming it "Star City".
Diggle and Lyla welcome a baby girl, which convinces Diggle to take Oliver's suggestion and retire from field duty.Oliver follows a lead and is able to identify the archer as Simon Lacroix. Meanwhile, trying to emulate Sara, Laurel attempts to exact vengeance on an abusive boyfriend of a fellow A. member, but she is overpowered and ends up in the hospital.The team learns of Lacroix's next target and intercepts him. As Oliver attempts to dissuade her, Lacroix reveals that he was not in Starling City at the time of Sara's death. to ascertain the whereabouts of one of its agents, Mark Shaw. Later, she seeks out boxer Ted Grant to train her to fight after Oliver's refusal.She quickly realizes that she designed the virus five years earlier, and that it is unstoppable.Her mother Donna shows up unannounced, and the two have a falling out over how different they are from each other.A cyber terrorist attacks Starling City, threatening to shut down all banks and set everyone on an even socioeconomic status.