The body of an unknown woman turns up in a stolen car abandoned in a New York park, and the only clue the detectives on the case have to work from is the tattoo on her arm, and the fact that someone tried to deface the corpse to remove the evidence. From this slender trail, and that of a single stem of grass discovered in the car, they gradually trace back first the victim and then her killer, in a case that's all science and legwork, and no magic inspiration.