Two Seattle espresso baristas, both young women, have been battered to death, and the Seattle Police have no clues. When a third victim is found murdered at midnight, her body lying in a rain-soaked alley, the SPD bring in their consultant on tough cases, Harley Wolf. They are envious of his astounding ability to sniff out clues, but if they knew the secret of his psychic-like deductions, they would persecute him more than the killer he hunts. Harley Wolf is a werewolf, a mythical monster of the night, but he is no killer. Haunted by the werewolf myths, he became a vegan at a young age, vowing to never hurt the innocent; instead he stalks the city's dark, rainy streets for killers who do. But even with his wolf prowess, he finds few initial clues to the Seattle Barista Killer, other than the faint trail he sniffs out of someone he calls, "The Marlboro Man," for the scent of the brand of cigarettes he detects on the body of the last murdered barista. That trail takes Harley deep into the murky world of the cutthroat espresso business, putting in danger even those closest to him. It pushes his caffeine-driven dark side to the edge, as he stalks a real monster that must be stopped before it kills again.