Joe and Cisco go to Starling City to ask Quentin Lance for his help investigating the site of Harrison's car accident 15 years ago and determining what really happened. Meanwhile, Eddie is framed for a shooting by a shapeshifing metahuman who can take on the appearance of anyone he touches.

Barry, Caitlin, Cisco and Joe set a trap for Wells. Cisco uses himself as prey which puts him in grave danger. Meanwhile, Eddie makes a decision regarding Iris, which leaves Joe a bit unsettled.

While Barry tries to find Eddie, a mysterious mind-controlled thief launches attacks on Central City's gold reserves. The team soon discovers that a telepathic gorilla is behind the robberies... and is following Harrison's commands. Meanwhile, Iris confronts Barry, while Harrison prepares to return home.

When Harrison activates the particle accelerator, the team has no choice but to evacuate the five metahuman prisoners. Unfortunately, with time running out, Barry has no choice but to turn to Captain Cold for help. Meanwhile, Eddie escapes but has some surprising news for Iris.

Wells presents Barry with a life-changing choice. Dr. Martin Stein and Ronnie Raymond return to help the S.T.A.R. Labs team with this final fight.