Barry continues to train Jesse and when a new meta human, Mirror Master, appears on the scene he lets her tag along. Mirror Master has teamed up with his old partner, Top, and is looking for Snart to even a score. Jesse is quick to join the chase but defies one of Barry’s orders which results in disastrous consequences.

Barry and the team at S.T.A.R. Labs work together to bring down Clive Yorkin, a criminal meta-human who is methodically killing people by causing them to decompose at an accelerated rate. Joe becomes his next target but it’s Iris who is caught in the crossfire. The Flash mentors Kid Flash and begins to elevate the newer speedster’s training to another level.

When Jesse Quick informs the team that her father has been abducted, Barry, Caitlin, Cisco and Julian voyage to Earth-2 on a rescue mission to save Harry from Gorilla City. As they trek through the forest, Barry and the team are immediately captured and brought to Grodd. Grodd tells them he needs their help to stop Solovar, the leader of Gorilla City, as Solovar wants to invade Earth-1. Meanwhile, back on Earth-1, Jesse and Kid Flash hit the streets to stop a metahuman that can control gravity, with H.R. and Joe guiding them from S.T.A.R. Labs.

When Grodd and his army of gorillas bring the battle to Earth-1, The Flash and team must find a way to stop them before they destroy Central City. Gypsy returns to join the fight. Meanwhile, Jesse Quick decides she wants to stay with Wally on Earth-1.

While training with Barry, Wally starts to have visions of Savitar, which he hides from the team. A dangerous secret threatens Barry and Iris’ happiness.

Desperate to stop Savitar and save his friends, Barry turns to the Speed Force for answers. H.R. gives Jesse some advice.

Barry and the team are hit by a string of bad luck and realize it is the handiwork of a new meta, Becky nicknamed Hazard, who has the ability to give others bad luck, while cashing in the benefits for herself. Meanwhile, Harry Wells returns to Earth-1 to give Wally a message from Jesse.

When a nuclear bomb detonates in downtown Central City, Barry, Jesse Quick and Jay Garrick slow down time by entering Flashtime. As everyone in the city is frozen, the three speedsters push themselves to the breaking point to save the city and everyone in it.