'The Flash': Is Grodd Part of Reverse-Flash's Master Plan?

Danielle Panabaker says the STAR Labs gang's cat-and-mouse game with their mentor has just begun: "He's from the future, so he can see many, many steps ahead of us."
Katie Yu /The CW

The STAR Labs gang is on the hunt for one of its own.

Tuesday's The Flash will see the team grapple with mounting evidence that their mentor, Dr. Wells (Tom Cavanagh), is the Reverse-Flash, the man who murdered Barry's (Grant Gustin) mother 15 years earlier.

Last week, Barry and his adopted father Joe (Jesse L. Martin) revealed their suspicions to Caitlin (Danielle Panabaker) and Cisco (Carlos Valdes). The investigation will take Cisco and Joe to Starling City to investigate what really happened to Harrison Wells. Viewers know that a man from the future, Eobard Thawne, murdered him and assumed his identity.

See more 'The Flash': Every Major DC Character on The CW Series       

"Wells is a genius, and he's from the future so he can see many, many steps ahead of us," Panabaker tells The Hollywood Reporter.

This week's episode, No. 19, is all about "Caitlin' s struggle," as she tries to come to terms with her mentor being a supervillain. The team's cat and mouse game with Wells will span multiple episodes, with Panabaker teasing that the much-anticipated showdown with psychic gorilla Grodd, set for episode 21, may be Wells' way of fighting his friends.

"In 20, we try to set a trap for Wells. Him being several steps ahead of us, he tries to trip us up, maybe with a giant Gorilla."

A preview for Tuesday's episode shows Joe and Cisco find the original Wells' corpse — a move that puts them in serious jeopardy of winding up just like it. Viewers know Wells will not hesitate to kill his friends, as he murdered Cisco for finding out his secret in an alternate timeline.

"Caitlin has this instinct to talk to Dr. Wells and confront him, and Barry pulls her aside and says 'let's think about that,' " says Panabaker. "If Barry is right, she is putting all of them in danger."

The Flash airs Tuesdays on the CW at 8 p.m.