You can read the synopsis for The Flash Season 4 here:
Barry Allen (Grant Gustin) lived a normal life as a perpetually tardy C.S.I. in the Central City Police Department. Barry’s life changed forever when the S.T.A.R. Labs Particle Accelerator exploded, creating a dark-matter lightning storm that struck Barry, bestowing him with super-speed and making him the fastest man alive — The Flash. But when Barry used his extraordinary abilities to travel back in time and save his mother’s life, he inadvertently created an alternate timeline known as Flashpoint; a phenomenon that gave birth to the villainous speed god known as Savitar, and changed the lives of Caitlin Snow (Danielle Panabaker) and Wally West (Keiyan Lonsdale) forever. With the help of his adoptive father, Joe West (Jesse L. Martin), his lifelong best friend and love interest Iris West (Candice Patton), and his friends at S.T.A.R. Labs — Cisco Ramon (Carlos Valdes), C.S.I Julian Albert (Tom Felton), and an Earth-19 novelist named H.R. Wells (Tom Cavanaugh) — Barry continues to protect the people of Central City from the meta-humans that threaten it.
The Flash Season 4 premieres on Sky 1 this autumn in the UK. A definite premiere date is yet to be announced. Get all the latest superhero news with every issue of SciFiNow.