Barry and Ralph must go undercover as criminals in an illegal black market to purchase a device that could help them stop Cicada. Once inside, Barry and Ralph find their morality tested as they slip deeper into the criminal world, eventually having to choose between committing a crime, or losing the means to defeat one of their greatest foes. Meanwhile, Iris investigates a lead on Cicada's whereabouts and ends up in a dangerous situation.

While Barry and Iris deal with the heartbreaking loss of their daughter, Nora, the team faces their greatest threat yet — one that threatens to destroy all of Central City. Meanwhile, Killer Frost has a brush with death that results in an unexpected new dynamic that will change her relationship with Caitlin forever.

Knowing that Crisis is only weeks away, Barry prepares a member of Team Flash for life without him while hunting a terrifying meta-human with an unquenchable thirst. Meanwhile, Ralph uncovers a family secret.