FBI profiler Maria Ruiz is done. Over a long career called in to consult on bizarre murders, she has chased the worst of humanity, scoured the depths of evil, and seen the limits of mortal justice. Once she finishes her last cases, she plans to leave the whole mess behind her.

When she connects two wide-ranging assignments, however, she knows something strange is happening. She becomes convinced that she’s following a mysterious assassin who stalks a series of high-profile targets: accused rapists and serial abusers, killers and corrupt politicians, all men who seemingly escaped justice. And as the bodies pile up, Ruiz comes closer and closer to catching the killer: an angel of death not from this world.