Former Syracuse, New York, police detective Carrie Wells has hyperthymesia, a rare medical condition that gives her the ability to visually remember everything. She reluctantly joins the New York City Police Department's Queens homicide unit after her former boyfriend and partner asks for help with solving a case. The move allows her to try to find out the one thing she has been unable to remember, which is what happened the day her sister was murdered.

Caitlin "Cat" Sullivan is an NYPD detective working in Brooklyn. After her driving privileges are suspended, she relies on Leo Romba, a highly skilled Brooklyn cab driver from France. Leo becomes Cat's driver and a consultant on her cases. While solving crimes with Leo, Cat is also running her own unauthorized investigation into the death of her father, an NYPD detective thought to have been executed by the Capella crime family. In doing so, she clashes with her boss, Captain Baker, and her ex-husband Gregg, who has picked up the case for the FBI.

Three gutsy kids from a rapidly gentrifying Bronx neighborhood stumble upon a sinister plot to suck all the life from their beloved community.