With crime at an all time low, Oliver decides to take a break and asks Felicity on a date. However, they're interrupted when a new drug dealer take the name of Count Vertigo and targets the Arrow for death. Meanwhile, Diggle becomes an expectant father and a scientist tries to acquire Queen Consolidated before Oliver can retake his family's business.
Oliver and his team try to find the archer who killed Sara, and discover that a hitman calling himself Komodo had connections to their friends past with the League of Assassins. Meanwhile, Ray continues trying to hire Felicity, and Roy debates whether to tell Oliver why Thea left Starling City.
Felicity tracks Thea to the island of Corto Maltese, and Oliver, Roy, and Diggle got here to bring her back. Meanwhile, Lyla asks Diggle to look into the disappearance of ARGUS agent Mark Shaw, and Laurel looks for an outlet for her frustrations.
Nyssa believes that Malcolm killed Sara and goes after him to avenger her lover's murder. Oliver discovers that he has no choice but to stop her, despite Laurel insisting that he avenger her sister's death. Meanwhile, Thea returns to Starling City and settles in... until Nyssa discovers that she's Malcolm's daughter.
Felicity's past as a crusading hacker is revealed when someone uses a super virus that she designed to bring Starling City to a standstill. Meanwhile, Oliver and Thea work on their new relationship, and Felicity's mother pays a visit.
A killer is murdering his victims and attempting to frame Ted Grant. The Arrow finally comes to his aid after Laurel protests her trainer's innocence. Meanwhile, Roy goes to Felicity for help determining if he killed someone under the influence of Mirakuru.
The Arrow is stalked by an ex-police officer who he rescued during the Mirakuru siege and has become dangerously obsessed with the hero. Meanwhile, Ray asks Felicity to accompany him to a business dinner, and Thea is forced to hire a new DJ for Verdant.
As Barry, Caitlin, and Cisco arrive in Starling City to help with the investigation into Sara's murder, former Suicide Squad member Digger Harkness goes after Lyla. The Arrow and his team need all the help that they can get to stop the boomerang-wielding killer, particularly when he sets five bombs in the city to cover his escape. In the past, Amanda Waller teaches Oliver how to make the hard choices... whether he wants to or not.
Ra's al Ghul sends Nyssa and her lieutenant to Starling City to inform Oliver that the League will kill 50 people a day until Sara's murderer is turned over to them. With time running out, Oliver finally identifies the killer... and realizes that he can never turn them over for execution. Meanwhile, Ray shows Felicity his new project.
With Oliver gone, Diggle, Arsenal, and Felicity have their hands full dealing with a new crime lord: Brick. Meanwhile, Ray prepares his battle armor, and in Tibet, a mysterious figure finds Oliver's body.
Brick takes three city aldermen hostage and demands that Mayor Castle turn the Glades over to him in return for their safe return. Meanwhile, Felicity turns to Ray for help when she needs a helicopter, and Laurel realizes that she may be in over her head with her new crime fighting carer.
Brick and his men take over the Glades, and the police are helpless to stop them. With Oliver nowhere to be found, the team seems helpless. Meanwhile, Oliver tries to convince Tatsu to return with him to Starling City, and Malcolm's past before his training at Nanda Parbat is seen.
Oliver forbids Laurel from going out on the streets to fight Count Vertigo, but she makes it clear that she will whether he approves or not. Meanwhile, Chase and Thea grow closer, and Quentin receives some shocking news. In the past, Amanda captures Oliver and tortures him for the location of Maseo's family.
Malcolm sends Oliver and Thea to Liun Yu to train, but they soon realize that he has a darker purpose when they discover that Slade has escaped. In the past, Amanda brings Oliver to Starling City to stop China White from auctioning off the virus, but Oliver is distracted when he discovers what has happened to his friends and family since his "death."
Songs: Flo Rida
-- You Spin My Head Right Round
Thea betrays Malcolm to the League, but Oliver sets out to rescue his lover's killer so that Thea won't suffer the guilt of arranging for a parent's death. In the past, Oliver and the Yamashiros are released from custody, but Amanda Waller has other plans.
Still weighed down by his last meeting with Ra's al Ghul, Oliver returns home to find a new villain and his crew have started terrorizing Starling City--Michael Amar AKA Murmur, a man whose mouth has been sewn shut. Meanwhile, Laurel and Nyssa bond over their issues with their fathers and Nyssa make Laurel an offer. Thea is forced to come to terms with her father after Oliver brings Malcom to the loft to recover, and Lance shuts out both Laurel and the Arrow.
Source: The CW