Still feeling responsible for Eddie's death, Barry pushes his friends away and tries to protect the city on his own; Cisco assists Joe with the Meta Task Force.
A mysterious man brings warning of an evil speedster intent on destroying The Flash, and a determined officer wants to join Joe's meta-human task force.
Barry and the team ally with the kidnapped Captain Cold's sister, but Barry feels duped when he learns Snart is working on something with his father; Joe faces a difficult decision.
Barry's team races to rescue Caitlin when Grodd abducts her; Cisco plans a date with the new barista at Jitters; Patty knows Barry is hiding something.
When Vandal Savage attacks Kendra Saunders, Barry takes Kendra to Star City, seeking Oliver's protection; Harrison asks Jay to test a new serum to make Barry run faster.
Believing Flash to be weakened, Weather Wizard returns to break Captain Cold and The Trickster out of Iron Heights Prison to form a triumvirate against him at Christmastime.
Barry and the S.T.A.R. Labs team hunt down The Turtle, who steals kinetic energy. Barry faces a choice on whether or not he should reveal his secret identity to Patty.
Dr. Wells figures out how to induce Cisco's ability; they hence learn that Eobard Thawne is still alive. Iris says farewell to her mother. Patty realizes there's more to Barry than meets the eye.
Barry tries to team up with Dr. Harrison but finds out Harrison prefers working alone. The Flash fights a new meta-human. Iris researches her brother's drag racing. Dr. Harrison starts stealing Barry's speed.
Harrison, Cisco and Barry travel to Earth-2 to save Harrison's daughter. Barry assumes the role of his doppelganger, who's married to Iris. He then encounters alternate-Caitlin and alternate-Ronnie, who are Zoom's agents.
On Earth-2, the team asks for help from an unexpected source to find Zoom's lair, while on Earth-1, Caitlin tries to perfect Velocity-9 so Jay can stop the Geomancer.
When King Shark escapes from an A.R.G.U.S. holding tank, Lyla and Diggle travel to Central City to warn The Flash. King Shark shows up at the West house and attacks Joe, Iris, Wally and Barry.
Just as Wells comes up with a plan to defeat Zoom, Zoom returns hellbent on destroying Central City. Meanwhile, Cisco has a vision of his brother, and Iris comes to terms with her feelings.
Zoom unleashes an army of Earth-2 meta-humans, the leader of which is Black Canary's doppelganger, Black Siren; Joe worries when Wally goes out to help The Flash.