Barry and Iris relive the same day over and over again. Joe has a heart-to-heart with Cecile. friends and foes, old and new, begin to descend upon Central City.

Barry feels guilty for what happened to Caitlin. Mark comes up with a plan that makes everyone skeptical. Red Death looms in Central City and commands that failure is not an option. Old friends pay an unexpected visit to S.T.A.R. Labs.

Barry recruits an unlikely team of allies to steal a valuable piece of equipment before the new Rogues can.

The Flash is forced to make an impossible choice; with the power out in the city, Team Flash calls upon the Rogue Squad to help. Iris is visited by an old friend. Joe and Cecile work on finding a balance.

Red Death unleashes her plan for total justice, with the aid of as-yet unseen ally.

Barry and Iris prepare for their new life. Cecile takes on a case involving a string of unfortunate and highly unexpected events. Chester and the team work with Khione to figure out her abilities.

Iris and Nia fall into a fever dream and explore different possibilities for their lives. Barry, Chester, Allegra and Cecile desperately try to help them. Khione feels that Mark is trying to make her something she is not.

A seemingly simple mold inspection at S.T.A.R. Labs leads to unexpected time anomalies. Chester admits a secret to Allegra, which makes things awkward between the two. Khione meets with an old friend of Team Flash.

Team Flash throws a surprise birthday party for Barry, but things go terribly awry when Ramsey Rosso crashes the festivities.

As Iris receives word of a career milestone, Barry is suddenly nowhere to be found. Barry runs across many familiar faces. Khione continues to figure out her powers. Chester works on a suit for Allegra.

Iris is alarmed by Barry's disappearance and Cecile assures her everything will be OK. Team Flash is affected by a mysterious substance. Khione develops a better understanding of what she can and cannot control.

Team Flash works together to figure out how to protect Barry, all while being very careful who they trust. Cecile is skeptical of the plan after an unsuccessful attempt. Khione's confidence in Chester enables him to convince Cecile to try again.

The Flash, the fastest man alive, is tasked with his greatest challenge yet to save the timeline and save existence. Friends old and new gather for an epic battle to save Central City, one last time.