The storyline of Flash Season 5 brings into the forefront of Barry Allen who is a CSI investigator. The series begins with Barry waking up from a coma after he was struck by a thunderbolt. He discovers that now he is capable of superhuman speed.
At an award ceremony, Barry confronts a group of armed men. However, he dwindles from the side effects of his newly acquired superpower. A vicious metahuman with capabilities of toxic gas is tracked by Joe and Barry. While Caitlin remembers the night of the explosion that killed her fiancé.
Captain Cold is bent on stealing a precious diamond and acquires a particular gun that can kill the Flash. Meanwhile, Joe does not like that Eddie and Iris are dating.