Coast City And The Guardian

During the Particle Excellerator fiasco, Rae Conner was in Central City with the Coast City police department, trying to catch Joy Killer, a serial murderer, who leaves his victims alive for the police to find, but they always die.
They had just caught Joy Killer, who's real name was Morgan Prisco, when the Dark Matter was released into the atmosphere, letting Morgan get away with the ability to turn invisible.
Rae was hit by a bolt of silver lightning and became a Speedster with a special kick.
Although she couldn't go over 500 miles an hour, with her fast healing abilities, she was able to heal others in minutes, and she could control electricity.
But being a superhero wasn't as easy as she had thought and it wasn't as easy as just saving people from burning buildings, like Barry, or hunting down corrupt CEO's and billionaires.

Morgan has figured out a way to recreate the Dark Matter and now there's a army of Meta-Human's tearing apart not just her city, but everyone else's too...