Bianca Salva, the brilliant and beautiful daughter of a renowned doctor, defies the conventions of the day by practicing medicine among the poor in her city. When she arrives at the home of a young courtesan, she is shocked to find a tragic scene: the lady has been murdered, stabbed with a dagger bearing the coat of arms of Ian Foscari, a handsome aristocrat renowned throughout Britain and Europe for his courageous escapades and his romantic conquests. Clutching the shining dagger, Bianca looks up to see none other than Ian Foscari himself.

In a heartbeat, the dashing Ian draws the obvious conclusion that he's caught the murderer redhanded. Bianca, meanwhile, mistrusts Ian and presumes he is guilty of the bloody killing.