An experiment on a simpleton turns him into a genius. When he discovers what has been done to him he struggles with whether or not what was done to him was right.

A young actress has retired from films to marry the son of a prominent and rich politician in New York City. The father objects strongly to the marriage. The actress is being blackmailed by a second-rate artist who has stolen some letters from her that could be misconstrued. During the payoff, she is knocked unconscious, and awakens to find herself involved in a murder and the police have her marked as the number-one suspect.

Lisetta, the daughter of a fisherman, lives with her father and brother on the island of Capri. When Serrani, an Italian who has grown wealthy in New York, visits the island, he induces Lisetta to accompany him to America. There he abandons her and she becomes a dancer in an underworld café owned by "Dago" Joe, where she meets the artist Stanford Graham, who employs her as a model. Meanwhile, Lisetta's brother Domenic comes to New York to avenge his sister's dishonor.