Caitlin brings Barry out to a karaoke bar, hoping they both meet someone new; Cisco thinks about Hartley's dangerous proposition; Henry's snooping gets him into trouble.
After Ronnie attacks a physicist, Barry and the team realize that he is now a dangerous meta-human and decide to track him down by finding Dr. Martin Stein.
Mark Mardon aka The Weather Wizard appears in Central City to avenge his brother's death at the hands of Joe. Cisco realizes that Dr. Wells is hiding something.
The Flash learns that Captain Cold and Heat Wave have returned to Central City. This time Snart has brought along his sociopathic baby sister Lisa to help wreak havoc on the city.
James Jesse, a.k.a. The Trickster, once terrorized Central City twenty years ago. Now a copycat has arisen to carry on the name and resume his murderous misdeeds.
Felicity Smoak and Ray Palmer come to Central City seeking help with Ray's suit; an ex-employee releases deadly robotic bees; a group dinner does not go as planned.
While Joe and Cisco travel to Starling City to find answers about Dr. Wells with the help of Captain Lance, Barry must capture a meta-human capable of transforming into the people he touches.
Barry, Caitlin, Cisco and Joe set a trap for Wells using Cisco as bait, which puts him in great danger. Eddie makes a decision regarding Iris, which leaves Joe a bit unsettled.
Knowing it's a deliberate distraction from Dr. Wells, Barry and those at S.T.A.R. Labs can't help but deal with an angry, mind-controlling meta-gorilla.
When Dr. Wells reactivates the Particle Accelerator, Barry must move the imprisoned meta-humans away. To do that, he needs help, and he chooses to ask Captain Cold for it.
Wells presents Barry with a choice. Dr. Martin Stein and Ronnie Raymond (aka Firestorm) return to help the team in their final standoff with the Reverse Flash.
