Harpya

A city dweller, out for an evening stroll, hears a woman's cries for help and rescues her from an assailant who is trying to drown her in a public fountain. However, when our mild-mannered hero pulls her from the water, she proves to be not a woman but a harpy - with a woman's face and breasts and the body of bird of prey. He takes her home and treats her like a human, but she is true to her nature, mercilessly and ravenously taking command of the household, dispatching his pet, and trying to make sure he can't leave. When he does manage, by a clever ruse, to get out of the flat and enjoy a snack, things don't go as he'd hoped.