Nightmare in Blood takes place during the first annual horror convention at the Palace Theater in San Francisco. Malakai (Jerry Walter), a legendary actor known for his vampire roles, is invited to appear at the convention which was organized by professor and mystery writer, Winslow Seabrook (Dan Caldwell), amateur sleuth Phillip "Scotty" Scott (John Cochran), and fashion designer Cindy O'Flahert (Barrie Longfellow). Malakai's publicity agents, Harris (Hy Pyke) and Billy "B.B." Boyd (Ray K. Goman), arrive with a contract that must be followed for Malakai to show up. Soon after Malakai arrives, people start disappearing. When the organizers discover that Malakai is a genuine vampire who is out to drain the blood from both fans and enemies alike, they band together with Tobias Ben-Halik (Irving Israel), who has chased Malakai and Harris and B.B. for the last twenty five years, to stop Malakai's diabolical plans before all of San Francisco is destroyed.