Control. Once you lose it, you'll kill to get it back.

Possessed by the Night (1994)

Directed by Fred Olen Ray

A horror writer buys an odd looking mutant embryo creature, pickled in a jar, from a shop in Chinatown, hoping it will be a creative inspiration for his work. Instead, the odd mutation provokes a rage of violence and lust to envelop the suburban villa where the writer lives with his wife and sexy secretary.