It’s Part 1 of a two part The Flash event where we get the show’s version of Planet of the Apes.
We learn from Jessie that her dad was lured to Gorilla City by Grodd. Everyone in Harry’s expedition group are dead and Harry is missing.
Barry realizes that Grodd having Harry is no coincidence (he can open a breach to Earth-1) and that it is part of the future headline of Central City recovering from a gorilla attack. Barry decides to go to Earth-2 to rescue Harry and prevent the headline from coming true.
Going on this journey is Cisco (to open the breach to Earth-2), Caitlin because she has a connection with Grodd and Julian who can’t turn down the chance to go to the Planet of the Apes in a parallel Earth. In reality, Julian is going to protect Caitlin from going all KIller Frost.
The team arrives on Earth-2 Gorilla CIty and tracking Harry’s watch. When they find it, they all realize it was a trap. Everyone is tranquilized and put into cells where no-one can use their powers.
Harry arrives but it isn’t him but Grodd speaking through him. Grodd tells Barry that since arriving he has been under the control of Solovar, the leader/dictator of Gorilla City. Grodd needs Barry to face Solovar so all the gorilla’s will no longer be under his rule. Also, Grodd tells Barry of Solovar’s plan to invade Earth-1 and asks Barry to help save his former home.
Barry eventually agrees to fight Solovar after meeting the white gorilla himself after getting him to promise to release everyone if he wins. In the arena, none of Barry’s Flash tricks work until he rapid fires his hand and takes down Solovar. Barry refuses to kill Solovar and shows him mercy. Grodd anticipates this and tranqs Barry and he is back in the prison cell.
We learn that Grodd actually wants to invade Earth-1 Central City because of Barry sending him to Gorilla City. Grodd wants Cisco to open up the breach. Harry awakens to all of this chaos. The team realize the only way out is if Cisco dies and Caitlin will do it by going all Killer Frost. Julian refuses to let that happen and Caitlin learns the real reason why he tagged along on the mission.
Barry agrees the only way to stop this madness if one of them dies. Later, Grodd comes back and see Caitlin weeping over Barry’s dead body. Grodd sees that Barry’s body is cold and drags him out of the cell and tosses him aside like a piece of garbage. Barry vibrates to warm his body and wakes up. Barry releases everyone on their cell and once free and clear of Gorilla City, Cisco opens a breach back to Earth-1 where Jesse is reunited with her father.
Speaking of Jesse, Barry asks her to remain on Earth-1 to help Wally protect the Central City and show him a thing or two at being a speedster. Before the team leaves on their rescue mission, HR comes into the STAR Labs and Jessie thinks this is her dad and gives him a big hug. Once Jesse learns the truth, HR is sorry to see the smile go away from Jesse’s face.
Wally is happy to have his girlfriend back on Earth-1 but it seems that Jesse isn’t feeling the same way especially after learning he has become a speedster. Even after stopping a robbery together, Jesse still is cold towards Wally. Later the two have a heart-to-heart. Jesse was hoping there was a way for them to stay in touch and she fears that before Wally became a speedster, he only liked her because of her speed. Wally assures Jesse that is not the case and wants her to stay with him on Earth-1. Jesse pulls away before giving an answer. [Fun Fact: I saw this scene being filmed back in December 2016 at the Vancouver Public Library Central branch]
HR finds Jesse and gives her some love advice that she does take to heart by asking what Wally would say if she asked her dad if she can move to Earth-1. Wally’s answer is to give Jesse a kiss. HR is pleased that Jesse took his love advice and when the lovebirds leaves, he mutters under his breath that Harry will be pissed.
With the team back on Earth-1, Caitlin tells Julian that while she likes him and likes the fact that he likes her, she won’t allow him to get close to her. Caitlin fears her powers and tells Julian to fear her too. Julian tells Caitlin that he will fear her and then says what helps him overcome his fears is a nice steak dinner and asks her out.
Back at Barry and Iris’, the two celebrate thwarting the future but little do they now that back on Earth-2 Gorilla City, Grodd has amassed a huge gorilla army and enlisted Gypsy from Earth-19 to open up a breach.