The case was this: Lawrence Horn hired a contract killer to execute his ex-wife and severely brain-damaged son. On March 3, 1992, the man he hired, an inexperienced killer named James Perry, used a book called Hit Man -- billed by the publisher as "A Technical Manual for Independent Contractors" -- as a blueprint for the murders; following to the letter the book's explicit instructions on how to make the killings look like a burglary gone wrong and...