Prof. Blinkwell, the suave, unscrupulous scientist and criminal mastermind, is back, this time visiting Paris. When Henri Reynard, the official investigating Blinkwell, is murdered in the hotel suite of the U.S. Ambassador, the prime suspect becomes Scotland Yard detective William Kindell, who's released when his identity is confirmed. But the Ambassador's daughter is kidnapped by Blinkwell's gang, and Kindell must race against the clock to save her. Will Prof. Blinkwell again escape the long arm of the law?