When an experiment to save Barry's speed backfires, Nash Wells searches for a way to save The Flash and comes up with a dangerous plan. Meanwhile, Iris makes a startling realization inside the Mirrorverse and Cecile faces off with Rosa Dillon.

When Barry suddenly gains the power of speed thinking, he attempts to use his new gift to save Iris. While Barry is thrilled with his new power, Cisco is hesitant to trust it. Meanwhile, Eva must face a shattering truth.

As Eva becomes more powerful, Barry and team must find a way to stop her. They are shocked when an old friend - Sue Dearbon risks her life to help.

The Flash must deal with Abra Kadabra's sudden return to Central City. The villain is back with a vengeance and a score to settle. Meanwhile, Allegra deals with a tricky situation and Caitlin suspects something is off with Frost. Iris is forced to look at a dark moment in her past.

Cisco and Chester travel back in time and get stuck in 1998, repeating the same day over and over again. The key to returning home is at Chester’s childhood home but he refuses to visit. Meanwhile, Iris forges a connection with the speed force.

When a mysterious ice powered enemy frames Frost for a brutal crime, she must find a way to clear her name. Meanwhile, Barry and Iris have a surprise houseguest, and Joe continues to deal with Kristen Kramer.