"Sam, could you do me a favor?" Thus begins a story that has now become part of America's true crime hall of fame. It is a gory, grotesque tale befitting a Stephen King novel. It is also a David and Goliath saga--the story of a young lawyer fresh from the Public Defender's Office whose first client in private practice turns out to be the worst serial killer in our nation's history.

Sam Amirante had just opened his first law practice when he got a phone call from his friend John Wayne Gacy, a well-known and well-liked community figure. Gacy was upset about what he called "police...