In Gotham City, where heinous acts of violence are a daily occurrence, the GCPD relies on Harley Quinn, a young forensic psychiatrist and profiler, to consult on their toughest cases. But Harley is haunted by one case in particular—when she found herself at the center of a horrifying crime scene the night she discovered the body of her roommate, left with the signature of a notorious serial killer—the Joker.

When a series of gruesome displays of murder appear throughout the city, the past and present collide as Harley’s obsession with finding the depraved psychopath responsible leads her down a dangerous path. She must decide how far she is willing to go, and what lines she is willing to cross to solve these cases once and for all.

(Illustrated by Mike Mayhew and Mico Suayan)