Season 03, Episode 17 – Duet
A crossover episode with “Supergirl” concludes. Barry and his team are surprised when Mon-El and Hank Henshaw arrive on their Earth carrying a comatose Supergirl who was whammied by the Music Meister. Unable to wake her up, they turn to Team Flash to save her. However, the Music Meister surprises The Flash and puts him in a similar coma. Kara and Barry wake up without their powers in an alternate reality where life is like a musical and the only way to escape is by following the script.
After a particle accelerator causes a freak storm, CSI Investigator Barry Allen is struck by lightning and falls into a coma. Months later he awakens with the power of super speed, granting him the ability to move through Central City like an unseen guardian angel. Though initially excited by his newfound powers, Barry is shocked to discover he is not the only “meta-human” who was created in the wake of the accelerator explosion – and not everyone is using their new powers for good. Barry partners with S.T.A.R. Labs and dedicates his life to protect the innocent. For now, only a few close friends and associates know that Barry is literally the fastest man alive, but it won’t be long before the world learns what Barry Allen has become… The Flash.