The Flash - Season 4 (2017)

Gypsy's father, Breacher, takes an immediate disliking to Cisco and decides to hunt him; Barry runs into his old nemesis, Ralph Dibny.

Caitlin fears that her past time as Killer Frost may be back to haunt her; Felicity helps celebrate Iris's bachelorette party, while Barry is taken out for a night on the town.

When Native American artifact collectors are attacked by a meta who can bring inanimate objects to life, Barry turns to a surprising ally for help. Harry enlists Cisco's help to determine the identity of the Thinker.

Barry comes face to face with DeVoe, whose past is revealed through flashbacks.

The gang comes together for Barry and Iris's wedding, but the ceremony is crashed by villains from Earth-X.

Amunet kidnaps Caitlin and forces her to perform a tricky medical task and the Thinker traps the Flash in a speedster-proof prison.

Joe and Iris must decide how far they're willing to go to keep Barry out of prison as his trial for the murder of Clifford DeVoe begins.

A familiar villain returns to terrorize Central City; Ralph must rise up to defend the innocent while Barry is detained by his trial.

The team battle a meta who can shrink anything he touches; Cecile's pregnancy gives her temporary powers.

Amunet makes a deal to buy all of the metahumans in Iron Heights, so Barry must decide if he should expose his powers to save his cellmates.

Barry meets a powerful woman whose abilities could help him in his battle with De Voe. Meanwhile after learning that De Voe is targeting everyone who was on the bus, Ralph decides he doesn't want to be a hero anymore, his only concern is staying alive. Harry offers to help Cecile, with her "problem", with Joe.

Barry, Jessie Quick and Jay Garrick slow down time when a nuclear bomb detonates in downtown Central City.

Iris is given Barry's speed when the team fights a bus meta who has the ability to swap people's DNA.

Barry and Ralph try to find the remaining bus metas, but clash over what it means to be a hero; Breacher returns to ask Cisco for a favor.

Barry and the team find a way into the Thinker's lair; Ralph considers crossing a dangerous line to defeat him; Joe is concerned by Harry's recent behavior.

When Barry needs help transporting a dangerous meta, he calls on an old friend for help - Leo Snart AKA Citizen Cold. Meanwhile, Cisco becomes suspicious of Harry.

Barry and Team Flash team up with Gypsy to try to thwart Thinker's plan. Meanwhile, Cisco and Gypsy have a heart to heart talk about their relationship.

The Flash and his team put their faith in an unlikely ally, Amunet Black, to defeat DeVoe; Harry hits an all-time low when the "Council of Wells" kicks him out but then Cisco introduces him to the "Council of Harrisons."

DeVoe assaults an A.R.G.U.S. facility to complete his Enlightenment Machine; Barry realizes the only way to stop DeVoe is to allow his friends to help; Barry is reluctant to risk his friends' lives and considers taking on DeVoe solo.

The team gets help from a surprising ally in their battle against DeVoe.