The mark of Cain (The Postman Always Rings Twice) may bar this from polite circles but the tricks here have news value. Jeff Allen, operating as a one-man murder incorporated, cleans up on unwanted wives and mothers, covers himself with respectability as a salesman for pharmaceutical companies, and, gambling on new business in Fort Worth, runs into obstacles for perfect executions. Involved in killing two women he is also given a straight big business chance and, diddled by fate, he loses out on everything-even living with himself. A sharp shocker.