he third season of Flash starts off where season two mysteriously ended. After Barry's trip back in time to save his mother using a changed timeline, one where he isn’t the Flash and that his parents are alive and well, he slowly loses his memories of the old timeline. This leads to him freeing the Reverse Flash to kill his mother and change the timeline back but, as we find out, changes things for the worse. He has a partner he doesn’t like at work, making life worse for his team one way or another and a new antagonist who brings villains from the other timeline into the current one.
The first half of the season is dealing with either the rouges or the villains. Dr Alchemy appears to be some sort of cult leader but someone more powerful, who isn't revealed until the midseason finale, is leading him. Dr Snow is also revealed to have been affected by Alchemy to become more like Killer Frost in season two. The Harrison Wells of this season is more flamboyant than the Reverse Flash and the snarky Wells from season one and two turns out to be a con artist and more of an author than a scientist.
The villains of this season are less well-known than those in season one and two with both returns and new rouges showing up like Mirror Master. There is a return of Grodd and a look into Gorilla City and the main antagonist Savatar is actually cobalt blue, who’s a version of Barry from the future who’s more evil.
The last half of the season is about trying to come up with a plan to stop Savatar from killing Iris. The original plan was to help Wally West, the new Kid Flash, train to become even faster then Savata but ends up being outplayed by trapping Wally in the speed force and freeing himself. Jay Garrick had to trade places with Wally to free him from the speed force. Harrison Wells traded places with Iris by using holograms to change their appearance to look alike each other and ends up with him dying in her place. Savatar is eventually stopped, but Barry had to go into the speed force to stop a speed force storm from destroying the city, which was created from a device that Savatar fired into the speed force.
Overall this season was the worst season of Flash. There was the terrible singing episode and also some questionable and illogical choices this season weird character interaction, like Cisco blaming Barry for his brother’s death even though he had nothing to do with it.