Team Flash gets help from a surprising ally in their battle against DeVoe.
When DeVoe assaults an A.R.G.U.S. facility to complete his Enlightenment Machine, Barry realizes the only way he can stop him is if he allows Cisco and Caitlin to accompany him into the facility. Still shaken by Ralph’s death, Barry isn’t sure he wants to risk any more of his friends’ lives and considers taking on DeVoe solo.
With DeVoe’s Enlightenment device nearly complete, in order to disable it The Flash and his team must put their faith in an unlikely ally – Amunet Black. Meanwhile, Harry hits an all-time low when the “Council of Wells” kicks him out but then Cisco introduces him to the “Council of Harrisons.”
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.
When Barry needs help transporting a dangerous meta, he calls on a new friend for help – Leo Snart; Cisco becomes suspicious of Harry.
When Barry and Team Flash find a way to enter The Thinker’s lair, Ralph considers crossing a dangerous line to defeat DeVoe. Meanwhile, Joe is concerned by Harry’s recent behavior.
Barry and Ralph take different approaches to finding the remaining bus metas before DeVoe gets to them. However, Ralph’s cavalier attitude frustrates Barry and the two clash over what it means to be a hero. Meanwhile, Breacher returns to ask Cisco for a favor.
Team Flash confront a new bus meta, Matthew Kim aka Melting Point. He has the ability to swap people’s DNA, so during a battle with Team Flash, he transfers Barry’s super speed to Iris. Now, with a new threat unleashed on Central City, Barry must act as the team leader while Iris takes on the mantle of superhero speedster in order to defeat their new foe.
When a nuclear bomb detonates in downtown Central City, Barry, Jesse Quick and Jay Garrick slow down time by entering Flashtime. As everyone in the city is frozen, the three speedsters push themselves to the breaking point to save the city and everyone in it.
Barry is let go from CCPD, due to his connection with the DeVoe case. The team encounter another Bus Meta, named Izzy (aka The Fiddler), who has the ability to manipulate sound; a power, which the team hope she can use to help them in their fight against DeVoe.