In the twilight of a mysterious childhood full of wonder, Billy Argo, boy detective, is brokenhearted to find that his younger sister and crime-solving partner, Caroline, has committed suicide. Ten years later, Billy, age thirty, returns from an extended stay at St. Vitus' Hospital for the Mentally Ill to discover the world full of unimagi-nable strangeness: office buildings vanish without reason, small animals turn up without their heads, and cruel villains ride city buses to complete their evil schemes.
Lost within this unwelcoming place, Billy finds the companionship of two lonely, extraordinary children, Effie and Gus Mumford--one a science fair genius, the other a charming, silent bully. With a nearly forgotten bravery, Billy treads from the unendurable boredom of a telemarketing job, stumbles into the awkward beauty of a desperate pickpocket named Penny Maple, and confronts the nearly impossible solution to the mystery of his sister's death. Along a path laden with hidden clues and codes that dare the reader to help Billy decipher the mysteries he encounters, the boy detective may learn the greatest secret of all: the necessity of the unknown.