

There's a new vigilante in town, the Deadly Nightshade, who fights crime by killing criminals. The Flash and the original Nightshade team up to take him down.
A laboratory accident endows a police scientist with the ability to move at superhuman speed which he uses to battle a menacing gang as a superhero.
Homeless people are dying and their bodies are disappearing. Tina rekindles a relationship with a former colleague who is an expert in genetic engineering.

The corrupt District Attorney Thomas Castillo hires a private eye named Megan Lockhart to find out the Flash's identity. He then blackmails Barry to work for him, or he'll expose his secret.