Hardened criminal Maggie Hayward's consistent violence, even in police custody, ends in the execution chamber. However, top-secret US government agent 'Bob' arranges a staged death, so Maggie can be elaborately trained as phantom killer and subdued into obedience. She gets a new cover identity as saleswoman Claudia Anne Doran. She also gets a wonderful house-mate, building super J.P., a broad-minded, gentle photographer. The two fall in love, and that complicates hit jobs. His good influence extends to breeding in her a conscience that places love over business, unlike Bob's agency.
