The industrialist's daughter has been kidnapped by the mad inventor Ravello, but Harry Peel stays hot on their trail with the help of his dog Greif. Behind a waterfall, he discovers the hidden gate to Ravello's castle, where the fiercest of battles now break out between the two and Harry finds...
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.
