David Nyki

Oliver meets the Canary. Oliver discovers a man who goes by the name "The Mayor" (guest star Cle Bennett) is bringing illegal guns in to The Glades, so Oliver sponsors a "Cash for Guns" event to help clean up the city. Unfortunately, The Mayor crashes the event with his gang and seriously injures Sin (guest star Bex Taylor-Klaus). The Canary is furious when she learns her friend is in the hospital and sets out for revenge. Meanwhile, Felicity stuns Oliver with a bit of information about the Canary's identity, Donner asks Laurel to dinner, and Diggle reconnects with an old friend.

Amanda Waller (guest star CYNTHIA ADDAI-ROBINSON) sends A.R.G.U.S. agents to kidnap Diggle. Waller informs Diggle that Lyla (guest star AUDREY MARIE ANDERSON) has gone missing after following a lead on Deadshot (recurring guest star MICHAEL ROWE) 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 (guest star TERYL ROTHERY), tells Thea that dating Roy, a known criminal, is hurting her mother's case.

Oliver is shocked when he learns that Slade has come to Starling City. Back on the island, as Oliver, Slade and Sara prepare to take over the freighter from Ivo (guest star Dylan Neal), Sara pulls Oliver aside and tells him he needs to kill Ivo to prevent him from telling Slade what happened with Shado. Oliver feels immense guilt over the situation but realizes Slade's growing rage from the Mirakuru makes him unpredictable and he could turn on his friends if he thinks Oliver is to blame. Oliver agrees to kill Ivo and the battle begins.

Oliver's world starts to crumble when Slade makes his move against Oliver – and the repercussions are enormous. While Oliver scrambles to protect his family, a key player in his team starts to question Oliver's decisions. Meanwhile, Isabel makes her move to take Queen Consolidated away from Oliver.

When Frank Bertinelli (guest star JEFFREY NORDLING) is arrested, Oliver knows it's only a matter of time before his daughter, Helena, aka The Huntress (guest star JESSICA DE GOUW), returns to town. To make matters worse, Laurel is picked to try Frank's case, putting her right in the path of Helena. Oliver tells Sara he will handle his ex-girlfriend, but when Helena takes hostages at the courthouse, including Laurel, the Canary will stop at nothing to save her sister. When The Huntress and Canary meet, an epic battle begins. Meanwhile, Roy realizes he needs to keep Thea safe, but doesn't like the way he is forced to go about it.