The telephatic Gorilla will kidnap Caitlin, and Barry with no speed powers will be helpless. Harry (from Earth 2) will wear the Reverse Flash suit to help Snow.
Meanwhile, the latest promo shows, Patty calling detective Joe and tells him, “Turns out our dead scientist cases are linked.” She explains that the scientist stole a large quantity of a drug, typically used to treat patients with vertigo.
To which, Joe says, “So we got two stolen drugs, one for blood disorders of the brain and the other one for Vertigo. What’s the connection?” Then, Patty replies that they are both drugs used to enhance intelligence.
Post which, Joe asks her whether she received the test results from the hair they had found. Patty reveals that the results are back and the hair match the hairs found in another crime scene and adds, “The weird things is they are not human hair, they are hair from a..” Joe cuts her midway and says, “Gorilla”. Joe immediately realises Grodd is back, and rushes to warn Barry and the Star Labs team.
We then see Barry in a wheelchair, and Cisco walks in and asks, “Did Caitlin come through here? She just hit me in the face and ran away.” We see Joe running and shouting, “Grodd!!! Grodd is back!”