An outlaw named Guerrero Hernandez is shot in the back and killed whilst attempting to free his half-brother from a small-town prison. Making a deal with the devil, Hernandez returns from the dead to take his revenge.

Darcy is a cop who is also a supehero named Black Scorpion at night who kicks and beats evildoers to a pulp. She soon catches wind of an asthmatic mad scientist who plans on tainting the city's air supply with a toxin. Only Darcy in her superhero garb can stop him with the assistance of a petty thief named Argyle.