Love is in the air. Barry makes Iris a romantic breakfast. At STAR labs, H.R. is decorating for Friends' Day, which is Earth-19's version of Valentine's Day. Harry has little use for H.R. and his sentiments. Cisco's feeling left out since he's not in a relationship. Caitlin insists she's not in one either. Jesse wants to tell her dad about moving to Earth-1.
Gypsy arrives and attempts to kill everyone. Harry stops her. She wakes up in a cell and doesn't remember attacking them. She'd been on Earth-2 to hunt a fugitive. Team Flash realizes Grodd hacked her mind. They also realize he must be on their Earth. Gypsy refuses to stay and help them fight Grodd.
Harry takes the news of Jesse moving to Earth-1 better than they assumed. In order to learn more about Grodd, he offers to alter Cisco's Vibe goggles. He asks Wally to help him. While they're working, he drops hints that he's sick and might not be around much longer. The Vibe works, but Grodd's tricked them. He takes over Joe and almost makes him shoot himself in the head. Barry saves him.
While Grodd kidnaps a general, Harry devises a way to get into Joe's mind. They discover the general and realize that he has the highest clearance to access nuclear weapons. A frustrated Barry thinks the only solution is to kill Grodd. Iris tells him that his humanity is not worth the cost of saving her life.
Wally attempts to talk Jesse out of moving. When he mentions her dad, Jesse sees right through him. Harry learns of Barry's plan to kill Grodd. Like Iris, he insists that killing Grodd is not the right call. He tells Barry there's always another way. Saving one life doesn't justify taking another.
Barry manages to disarm the missile. But the three speedsters can't hold off the gorilla army on their own. Cisco travels to Earth-19 to ask Gypsy for help. She's reluctant, but he's confident there's a hero in her. As the gorillas beat Barry, Wally, and Jesse. Gypsy arrives with Solovar. He challenges Grodd. The two fight and Solovar wins. He makes a move to kill Grodd, but Barry stops him.
He asks Solovar to spare Grodd's life like he spared his. He says they will keep Grodd on Earth-1. Solovar agrees and takes the gorilla army back to Earth-2.
Gypsy kisses Cisco goodbye and says he couldn't handle her. Cisco tells his friends he's going to marry her. As Harry gets ready to go back to Earth-2, he asks Wally to be good to Jesse or he'll hunt him down. Wally agrees.
When Iris returns home, Barry's decorated the apartment with candles. He tells her that he's not going to worry about the future he saw. He wants a future with her. He proposes.
Jesse and Wally are cuddling as they argue over movies. She sends him out for Big Belly Burger and he's intercepted by Savitar.