When a dangerous criminal from Lance's past (MICHAEL EKLUND) escapes from prison, Felicity offers herself up as bait so Arrow, Diggle and Lance can capture him...but plans go awry.

While Oliver tends to the Canary's wounds, he tries to get her to talk about where she came from but she refuses. However, after Oliver and Canary are attacked at the Queen mansion by a trained killer from the League of Assassins, she confesses to how she's connected with the nefarious group. Meanwhile with Moira facing multiple counts of murder and conspiracy for her part in the destruction of The Glades, the Assistant District Attorney offers her a choice - plead guilty now and avoid the death penalty or take your chances in court. Thea begs her mother to fight for her life but Moira seems resolute about taking the offer. Meanwhile, Oliver is furious with Laurel for joining the prosecution's team on his mother's case.

Amanda Waller sends A.R.G.U.S. agents to kidnap Diggle. Waller informs Diggle that Lyla has gone missing after following a lead on Deadshot in Moscow. When Diggle tells the team he's headed to Russia to rescue Lyla, Oliver and Felicity decide to join, but things get messy when Isabel shows up on the tarmac and insists on joining Oliver's "work trip". Meanwhile, Moira's lawyer, Jean, tells Thea that dating Roy, a known criminal, is hurting her mother's case.

Oliver is concerned when a mysterious illness sweeps the city, infecting hundreds of people, including Diggle. Oliver discovers Vertigo in Diggle's blood and realizes The Count has broken out of prison and is once again distributing his drug. Meanwhile, Moira goes on trial for her participation in the Undertaking. ADA Adam Donner collapses in court with Vertigo symptoms so Laurel must step in and try the case against Moira. Oliver is torn between standing by his family during the trial and catching The Count. However, things change when Felicity follows a lead and walks straight into a trap set by The Count.

Oliver celebrates Thanksgiving with his family but the happy moment is interrupted. Meanwhile, Black Siren returns to wreak havoc on the holiday.

Roy Harper returns to Star City and Oliver and Thea take action to save him when they discover the reason why he's come back.

The pressure mounts for Oliver who begins to wonder if he will lose everything in his battle to save Star City. A familiar face returns.