Oliver still hasn't figured out how to get back in Laurel's good graces, but a late night bonding session with Thea gives him the inspiration he needs. Looking into a suspicious murder case, Oliver realizes an innocent man, Peter Declan, was framed by one of the targets on his list. As Arrow, he asks Laurel to help prove Declan's innocence. Meanwhile, Walter asks one of his employees, Felicity Smoak, to look into a $2.6 million withdrawal that Moira made without his knowledge.

Oliver encounters a mysterious woman, Helena Bertinelli, daughter of mob boss Frank Bertinelli, who he can finally be himself with, but he soon comes to realize she's hiding dangerous secrets of her own. Helena is on her own personal mission of vengeance and Oliver is caught in the middle. Meanwhile, Tommy is blindsided by an unfortunate turn of events and turns to Laurel for support.

Oliver’s confidence is shaken after being beaten by the Dark Archer and he takes a break from being Arrow. However, when Laurel calls Arrow for help investigating a firefighter’s suspicious death, he reluctantly agrees but his hesitance while fighting almost costs him his life. Meanwhile, Tommy throws a benefit for the firefighters and Thea tries to lift Moira out of her depressive state.

Cyrus Vanch, a nefarious criminal, is recently released from prison and intends to re-secure his position as leader of the underworld. His first step is to take down his biggest opponent in the city - Arrow. Meanwhile, Oliver shows Moira his father's notebook and questions her about the names on the list. Thea is miserable as she starts her internship with Laurel at the legal aid office and Detective Lance makes a deadly mistake that puts Laurel in the crosshairs of Vanch.

With the Undertaking days away, Malcolm dons his black hood to conclude business with seismologist Dr. Brion Markov and his team. Oliver and Moira entertain a number of surprise - and mostly unwelcome - visitors. Hooded confrontations at home and the Meryln Global Group reveal dark secrets. Meanwhile, Roy and Thea are still looking out for a hero. Laurel makes a decision after Tommy's revelation. In a flashback to the island, Oliver, Slade and Shado struggle to prevent Fyers from shooting a Ferris Air jet out of the sky. Paul Blackthorne and David Ramsey also star.

When a superhumanly strong thief robs a Queen Consolidated warehouse, Central City police scientist Barry Allen comes to Starling City to investigate the case. However, despite his close working relationship with Felicity, Oliver suspects that there's more to the young scientist than meets the eye. Meanwhile, Sin asks Roy to help investigate the disappearance of a friend. In the past, Oliver, Shado, and Sara try to get Slade to the submarine so they can use the serum to save his life.

After the death of someone close to him, Oliver decides to give himself up to Slade rather than risk further bloodshed on his friends and family. Meanwhile, Laurel renews her investigation into Sebastian Blood, and Slade makes his final plans to unleash his Mirakuru-enhanced army on Starling City.