Season synopsis
Contains spoilers for this season and earlier seasons.
After Oliver Queen returns to Starling City, he uses a list left by his father to target people whose corruption has harmed the city. At first he works alone, hiding his identity from his mother Moira, sister Thea and childhood friend Tommy Merlyn, while John Diggle becomes his bodyguard and then his partner. Computer specialist Felicity Smoak helps the team, and Laurel Lance, now a lawyer, remains tied to Oliver through their shared history and to her father, Detective Quentin Lance, who hunts the hooded vigilante.
The targets lead Oliver to a conspiracy involving Moira and businessman Malcolm Merlyn. Malcolm plans the Undertaking: a machine that will trigger an earthquake and destroy the Glades, where his wife was murdered. Oliver learns Malcolm is the Dark Archer, but his attempts to stop him are complicated by Tommy, who leaves Laurel after discovering Oliver’s feelings for her. In the island flashbacks, Oliver’s captivity with Yao Fei and Slade Wilson turns him from a shipwrecked survivor into a fighter, while the present-day team grows around him.
Moira publicly admits her role and warns residents to flee; Quentin and Felicity disable one device, but Malcolm’s backup destroys part of the Glades. Oliver fights and apparently kills Malcolm, then reaches Laurel’s collapsing building too late to save Tommy, who dies after rescuing her. The loss shatters Oliver’s belief that he can protect everyone and shapes his vow against killing in the next season. The earthquake kills many residents, leaving Starling City’s recovery and the team’s changed methods unresolved.