The appearance of dangerous black holes around the city leads Team Flash to a comatose vlogger, while Iris and Barry struggle to come to terms with their recent loss. Meanwhile, Caitlin attends a funeral that brings her back into the life of an old friend -- a scientist who is pursuing unorthodox research to cure disease.
Facing his impending death, Barry attempts to travel into the future to witness the coming crisis firsthand -- sending him to Earth-3 for help from Jay Garrick. Meanwhile the team pursues a troubled meta-human girl suspected of a crime, and Cecile finds herself in conflict over her role as a prosecutor.
Amidst a series of attacks by a meta-human with a thirst for dark matter, Barry recruits Frost for help in his investigation. Meanwhile Ralph and Cecile come to the aid of Ralph's mother, and another Harrison Wells turns up in Central City.
Cisco finds himself at cross purposes with Barry when he refuses to give up trying to save his life. Ramsey Rosso exploits his deadly new abilities to save his own life.
When Breacher shows up to deliver bad news about his daughter, Cisco finds himself under suspicion for a horrific crime. Killer Frost continues to try and stop Ramsey, and Joe finds himself trapped with "Nash" Wells.
Barry joins Ralph on a trip to Midway City, where a breakthrough on a long-simmering missing persons case takes them inside an auction for the super rich. Cecile attempts to use her powers to help Chester P. Runk get his life back on track, and Wells turns to Iris' new intern for aid.
Facing his imminent demise in the coming crisis, Barry finds himself hallucinating Ramsey Rosso -- who claims that Barry can save himself and everyone he loves by giving in to the infection now spreading through his body.
Team Flash finds itself running out of options when they must go up against Bloodwork, a city of blood-infected citizens, and their most dangerous enemy ever -- the Dark Flash, Barry himself under Ramsey's control.
Barry leads a team to discover the shocking source of the anti-matter wave, as John Constantine leads Mia and Diggle into Purgatory. Kara contemplates a dangerous way to bring back her loved ones, and Iris is sent to recruit the final Paragon -- a young scientist living on Earth-1.
Iris' investigation of a shadowy group trafficking in metas and meta tech makes her the target of a high-powered assassin. Meanwhile, Barry and John Diggle travel to Lian Yu in the hopes of finishing one last mission for Oliver.
Barry finds himself pushed away by Iris, who takes it upon herself to thwart Amunet's efforts to steal valuable tech before her former boyfriend gets to it first. Frost tries to play matchmaker for Allegra.
Ralph finally finds his long-missing person, Sue Dearbon, and finds himself teaming up with her on a daring adventure to stop the gangster who is trying to kill her. Meanwhile Iris finds herself trapped inside a mirror prison, where a despondent Eva McCulloch has given up all hope of escape.
Barry is drawn into a mental prison, where his former foe Grodd is seeking his help. Eva shows Iris why she believes they cannot escape from the Mirrorverse, and Allegra learns about Nash's special interest in her.
Wally West returns home with a warning that something is wrong with the speed force, prompting Barry to take extreme measures. Meanwhile a meta with the ability to manipulate time attacks a Russian socialite, aging her victim to death.
Cisco attempts to save Nash after the team discovers that other Wells were fused within him after Crisis -- including Eobard Thawne, who is fighting to take control. Meanwhile the Flash takes on a dangerous Black Hole operative, code-named Sunshine, knowing that he now has a finite amount of Speed Force left in him.
Joe West finds himself the target of a Black Hole assassin -- the merciless Rag Doll, who captures someone close to Joe to lure him into a trap. Ralph and Cisco cross paths with Sue, while Eva continues to plot her revenge from the mirror world.
Barry becomes convinced that Iris is not the woman he knows, but finds it difficult to convince the others that she is an imposter -- while Eva plans her final move. Meanwhile Ralph and Cisco discover an ailing Caitlyn nearly frozen inside her apartment.
Godspeed returns demanding Barry's speed, Team Flash seeks help from Hartley Rathaway -- a sonic-powered villain who holds the Flash responsible for a personal tragedy. Iris finds an ally inside the Mirrorverse, and Ralph gives counsel to Frost.
When Eva marshals her forces to go after her husband, Barry and the team must protect Carver from her quest for vengeance. Ralph is reunited with Sue, only to find her about to make a mistake that could haunt her forever.
