Using his marauding robot and other futuristic weapons, power-crazed scientist Professor Ravello carries out various plots to win the hand of Evelyn away from her true love Harry Peel.

A black envelope presents the hero, detective Harry Peel, who loses his fortune over the course of the story, with tasks. A mysterious criminal, car and motorcycle chases through the wintry Alps, and the blowing up of a bridge provide cinematic spectacle and opportunities for daredevil stunts.