A timid, nearsighted chemistry teacher (Jerry Lewis) stumbles onto a magical potion in his lab. The mixture transforms the scholarly knucklehead into a suave and smooth-talking Romeo. The object of his debonair attentions is the gorgeous blonde from his class (Stella Stevens). This Jekyll and Hyde concoction works well enough it wears off at the most embarrassing times, and the amorous suitor suffers hilarious symptoms of his personality split.