In the first episode, Barry, Caitlin Snow, Cisco Ramon, and Julian Albert travel to Earth-2 to rescue Harry Wells from Gorilla City.
His daughter Jesse Wells explains to Team Flash on Earth-1 that her father was leading an expedition to Gorilla City which was ambushed and killed while Harry disappeared.
Barry Allen remembers the news report during his visit in the future, in which it was revealed that Central City will be attacked by gorillas.
Harry subdues Gypsy when she ambushes and tries to kill Cisco and Barry, and the team realizes that Grodd and his forces have reached Central City.
[1][2] In January 2016, executive producer Andrew Kreisberg said that he intended to wait to tell the next chapter of Grodd's story for a multi-episode arc.
He compared Gorilla City to the storyline of Ra's al Ghul and Nanda Parbat from Arrow, noting "it's a long-term thing".
In August 2016, Kreisberg confirmed Grodd's return in the third season of The Flash, saying, "Yes, we're going to be doing a two-part episode that takes place in Gorilla City.
The second part, "Attack on Central City", would be written by Benjamin Raab and Deric A. Hughes based on a story by Todd Helbing.
[7] Carlos Valdes called the episodes' tone "one of fear, because when you suddenly find yourself in the cold African jungles of Earth-2 and you hear the sound of omnipresent gorillas roaring at you, it kind of makes you shake in your boots".
In January 2017, Keith David was cast to voice Solovar, a longtime ally of the Flash in DC Comics and the leader of Gorilla City.
[10] In "Attack on Central City", Sean Poague appears as Accelerated Man, a speedster and Earth-19's version of the Flash,[11] and Paul Jarrett was General McNally;[12] both received co-starring credit.
[19] Due to a prolonged snowfall in Vancouver, filming of the "Gorilla City" scenes had to be moved south of the original site.
Club wrote, "The two-part Gorilla City adventure serves as a showcase for ambition outstripping budget and ingenuity.
Berlanti and company clearly want to deliver on the goofy anything-goes appeal of DC's Silver Age, and it's to their credit that they keep trying to pull off these fan-friendly events.
The closest it comes is the closing scene, with Grodd and his troops clad in full battle armor, having found a way to invade Central City after all ...
The trip to Earth-2 infuses The Flash with a level of suspense that's been missing for awhile, and it's clear from director Dermott Downs' many sweeping shots of the completely CGI'd Gorilla City that he's relishing the opportunity to transport viewers to this part of the DC Universe ...
The fight between Solovar and The Flash was impressive, especially for a CW show, as the stadium visuals reflected the epic scope of the event for Gorilla City".
[34] Giving "Attack on Central City" 8.5 out of 10, Schedeen said: "The Flash wrapped up an ambitious two-part storyline in fine form this week.
He added, "The slugfest between Grodd and Solovar up and down the side of a skyscraper plays a bit like a cut scene from a King Kong video game, but it comes as a relief after the largely action-free episode leading up to it".
It managed to play well on the series strength, though it was also hampered by some pacing issues ... "Attack on Central City" was certainly ambitious.
Dedicating an episode to the Flash team dealing with an army of sentient, super-powered apes from an alternate reality is a storyline that you'd expect from a comic book, but not so much from a prime time television show.
Understandably, the show's budget didn't allow for the entire episode to be devoted to Flash fighting a telepathic gorilla twice his size, but thanks to the strength of the characters, we're able to forget about the special effect shenanigans and focus on the interactions they all have with one another".
He gave the episode four stars out of five, praising "the 'balls to the wall' method that the creators have taken in attempting to bring a comic book to life here".