Powers is a police procedural comic with a science fiction twist. In a world, where superpowers are common, but not completely everyday, Christian Walker and Deena Pilgrim are police officers that deal with homicides that involving "powers" (a slang term for superhumans).
Walker used to be a "power" himself and was a superhero called "Diamond". However, he lost his abilities and became a police officer. Despite the latter, he still has contacts in the superhero community.
Deena Pilgrim, his partner, has a dark secret: she managed to get superpowers to battle a super villain called Bug, but this led her to accidentally kill her abusive boyfriend in self-defense and she hid the evidence. However, she manged to redeem herself later in the series.
Gotham Central focused on the cops in titular city and their interactions to superhumans.
Alan Moore's Top 10 was also about superpowered cops solving cases involving superhumans, which worried the creators of Powers. However, Moore said the series were different as Top 10 is about "superpowered cops" where as Powers is about cops that deal with superhumans.