It's Halloween, and John Justin Mallory's partner, Winnifred Carruthers, has been so busy preparing for the biggest holiday of the year (in his Manhattan, anyway) that she seems short of energy and pale. Mallory is worried that she's been working too hard. Then he notices the two puncture marks on her neck...

On this night when ghosts and goblins are out celebrating, detective Mallory must stalk the vampire who has threatened his assistant, Winnifred Carruthers, and killed her nephew. With the aid of Felina, the catgirl, Mallory and Carruthers investigate clubs and lairs that only seem to exist on this one night of the year.

His hunt takes him to Creepy Conrad's Cut-Rate All-Night Mortuary, where he questions the living and the dead; to the Annual Zombies' Ball, to learn more about the undead; to the Hills of Home Cemetery, where the vampire sleeps by day; and to Battery Park, where all of Manhattan's bats come to feed and sleep. Along the way he meets a few old friends and enemies, and a host of strange new inhabitants of this otherworldly Manhattan.

Locked in an intriguing battle of wits with the millennia-old vampire, Mallory has until dawn if he is to save his trusted partner.