In contemporary wartime San Francisco, chemist and extortion Albert Baker is killed by hit man Philip Raven, who recovers a stolen chemical formula. Raven is double-crossed by his employer, Willard Gates who pays him with marked bills and reports them to the Los Angeles Police Department as stolen from his company, Nitro Chemical Corporation of Los Angeles. Raven learns of the setup and decides to get revenge. LAPD detective lieutenant Michael Crane, who is vacationing in San Francisco to visit his girlfriend, nightclub singer Ellen Graham, is immediately assigned the case. He goes after Raven, but the assassin eludes him.