Engelein is a comedy of deliberately mistaken identity. If Jesta, a 17-year-old, can play the part of a 12-year-old, her family will gain a large inheritance from a rich uncle from Chicago. Her unruly “play-acting” for the uncle is preceded by an earlier incident in the film that results in Jesta being evicted from her girl’s school. Wearing a long, woman’s skirt, she climbs up a ladder and onto a thatched roof. She reaches over the top of the wall to kiss her boyfriend, who appears from the other side. However, Jesta is caught by the headmistress, and her forced descent is precipitous. Pulled downward, she reveals a great deal of a black-stockinged leg. She looks distinctly sexual as she falls into the matrimonly arms of the law, whose duty is to enforce the rules of female decorum.

Suddenly appearing in Florence, an evil seductress causes Cesare, the city's ruler, and his son to both fall madly in love with her. The son, killing his father before an order to torture the woman can be carried out, then turns the city's churches into dens of sexual debauchery. Acts of evil and corruption continue unabated until the arrival of Death, who brings with her a horrible plague which she is about to loose upon the city.

The daughter of a daimyo, one forced to commit harakiri to secure her a future to choose her own destiny, falls in love with and marries a European officer. The officer returns to Europe but promises to come back for her and his new child, but when he comes back to Japan, he brings his European wife.