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.

Team Flash confront a new bus meta, Matthew aka Melting Pot. He has the ability to swap people’s DNA, so during a battle with Team Flash, he transfers Barry’s super speed to Iris. Now, with a new threat unleashed on Central City, Barry must act as the team leader while Iris takes on the mantle of superhero speedster in order to defeat their new foe.

When Ultraviolet returns to Central City, Allegra is determined to find her cousin and change her heart. Meanwhile, Joe finds evidence that Kristen Kramer may not be the good cop she appears to be.

After returning home from a visit for their parent's vow renewal, Bart and Nora quickly realize that things are not exactly as they left them. The duo race to repair any fissures in the timeline and restore everything back to the way it is supposed to be.

Having received an ominous threat from her old boss, Amunet, Caitlin fears that her past time as Killer Frost may be back to haunt her. Felicity comes to Central City to help the girls celebrate Iris's bachelorette party, while Cisco, Joe and the guys take Barry out for a night on the town.

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 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.

Cecile is forced to confront her past in order to break free from a psychic prison. Meanwhile, Chester takes over for Cisco but makes a mistake that puts Barry in serious danger. Joe investigates Kristen Kramer's old military ties and discovers an unsettling truth.

Barry and Team Flash get closer to figuring out the Fire Meta but no closer to finding him meanwhile Iris, needing a distraction, follows a story to Coast City.

The Flash goes off the grid to look for answers about a new Meta in town. Meanwhile, Allegra pulls out all of the stops at CC Citizen Media, to protect a source and a friend.

After a devastating betrayal, Barry turns to Timeless Wells for help. Meanwhile, Iris leads Team Citizen down a dangerous road in search of answers, and Cisco confides his biggest fear to Kamilla.

Barry and Iris come together to try and stop a dangerous force from destroying Central City.

With The Flash still reeling from everything that just happened, the rest of the team rallies to support him when he needs it the most.

Cisco and Kamilla tell the team they are leaving Central City. However, Barry, Iris and Caitlin don't have much time to digest the news because a new version of Rainbow Raider strikes and OG Team Flash must join together one final time to save the city.

John Diggle arrives in Central City with a weapon to help Barry stop the Godspeed War. Meanwhile, Allegra and Ultraviolet's new bond is put to the ultimate test, while Joe and Kristen Kramer are hunted by a former colleague of hers.

Team Flash uses the distraction of a bank robbing Meta to detract from the grief of losing someone they love.

During a battle with Cicada, Nora is severely injured. Due to Cicada's dampening powers, Nora's speed healing isn't working, leaving Barry and Iris scared for their daughter's future. Upset about his injured child, The Flash is filled with rage and confronts Cicada in a brutal battle. Meanwhile, Killer Frost keeps interfering with Caitlin's work on the cure.

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.

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.

Iris is pushed to the limit as she seeks to uncover the mysterious truth about Psych; Barry initiates a new training system, that could potentially backfire, with devastating consequences; Joe and Cisco make life-altering decisions.

Barry has his hands full when he takes on a dangerous meta who can control technology, while also confronting an obstacle in his personal life: the ramifications of abandoning Iris for six months to balance the Speed Force. Meanwhile, Gypsy breaches in for a hot date with Cisco, but she gets annoyed when his work keeps them apart.

Nora lets something slip about the future that devastates Iris. In an attempt to distract his wife, Barry asks Iris to team up to stop a new meta, Rag Doll. Meanwhile, Caitlin learns something about her father.

An opportunity presents itself for The Flash to end his lifelong battle with Reverse Flash for good, but the payoff could be too much for Barry and team to handle. Meanwhile, Mia Queen drops in from the future looking to save a lost loved one, and she won't let anything stand in her way.

With a new Meta terrorizing the city, Joe lends a hand to the local authorities, meanwhile Barry gets an assist from Cecille who helps to track the mass murderer.

The Flash gets an assist from XS. Meanwhile, CCPD enlists Chester for help when a mysterious device is found at a crime scene.