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.

Seemingly impossible robbery at Queen Consolidated's Applied Sciences Division brings Central City police scientist Barry Allen to town. Citing a similar case back home, Barry offers to help Oliver and team with the investigation. Oliver senses there is more to Barry than meets the eye, but he's distracted by the similarities between this current case and something that happened on the island. Meanwhile, Felicity takes a liking to Barry, which doesn't go unnoticed by Oliver. Sin asks Roy for help when a friend of hers goes missing. Roy is surprised when Thea not only encourages him to help, but joins the search. Unfortunately, Sin's friend is connected to Brother Blood, and their search ultimately gets one of them seriously injured.