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.

Barry's efforts to prepare Cisco for Crisis are derailed when Cisco schemes to save Barry's life instead. Meanwhile, Ramsey Rosso uses his deadly new abilities to save his own life, while sacrificing his humanity in the process.

Cisco's faith in his ability to fill Barry's shoes as Team Leader is upended when he learns of a shocking murder. Meanwhile, Killer Frost trusts no one except herself to hunt down the dangerous Ramsey Rosso.

Barry turns his attention to prepping Elongated Man for life after Crisis and without The Flash, but Ralph ultimately teaches Barry a lesson. Meanwhile, Cecile faces her own moment of self-discovery while helping a recuperated Chester P. Runk reclaim his identity.

As Barry Allen stands on the threshold of his impending death in Crisis, his convictions are tested when the monstrous Dr. Ramsey Rosso infects The Flash with a mysterious, hallucinogenic contagion. Meanwhile, reporter Iris West-Allen uncovers a vast conspiracy.

With The Flash freshly infected by the monstrous Bloodwork, Iris and Cisco battle to help Barry take control of himself before he’s lost forever to Ramsey’s influence. Meanwhile, the rest of Team Flash fight to reclaim control of Central City from Bloodwork’s growing army.

Pariah enlists Black Lightning to help stop the Anti-Monitor after Flash-90 shares what he learned from his battle in ‘Elseworlds.’ With the help of Black Lightning, Barry, Cisco and Killer Frost come up with a plan that could save them all. Meanwhile, Iris has a heart-to-heart with Ryan Choi, while Oliver and Diggle return to an old familiar stomping ground.

The crossover starts on Supergirl S05E09 and Batwoman S01E09. It continues on Arrow S08E08 and Legends of Tomorrow S05E01.

After "The Citizen" prints an explosive story, Iris' life is threatened; refusing to hide from her attackers, Iris sets out to expose a dangerous organization; Barry must face the consequences of the Crisis and fulfill Oliver Queen's wish for him.

Barry and Iris plan a romantic dinner for Valentine's Day but their evening is interrupted by an old foe - Amunet; Frost gets into the holiday spirit and attempts to help Allegra reconnect with an old love.

After months of searching for Sue Dearbon, Ralph gets a lead on her whereabouts and finally comes face to face with his missing client. However, Sue refuses to return home to her family, and instead, takes Ralph on a daring adventure. Iris faces a new challenge while Barry considers a potentially dangerous request from a trusted source.

Feeling overwhelmed with all the changes since Crisis, Barry conducts an experiment that goes awry and puts him directly in Gorilla Grodd’s path. Expecting the worst, Barry is surprised when Grodd asks for his help. Unfortunately for both The Flash and Grodd, things get worse when another villain appears – Solovar. Meanwhile, Iris works with Eva to escape the Mirrorverse.

Kid Flash returns to Central City with a Zen attitude and new tricks up his sleeve. While thrilled to see his family again, Wally confides to Barry that he returned because he thinks there is something wrong with the speed force. Meanwhile, Cisco returns from his fact-finding mission across Earth-Prime.

The Flash takes on a dangerous new meta named Sunshine. Cisco sets out to help Nash.

After Black Hole hires Rag Doll to kill Joe, Singh suggests he go into Witness Protection but Joe refuses to stop investigating Carver. While investigating Carver with Cisco, Ralph runs into Sue. Iris becomes suspicious of Eva.

After recent events, Barry takes a closer look at his life with Iris. Eva makes a bold move.

When Godspeed returns, Barry turns to Hartley Rathaway for help. However, things get tense quickly after Barry realizes one of the changes from Crisis is that The Flash and Pied Piper are now enemies. Meanwhile, Iris tries to escape the Mirrorverse.

Barry considers a risky plan to save Iris from the Mirrorverse. Ralph attempts to stop Sue from making a grave mistake that could destroy her life.