Julian Hammer wrote thrillers. When people asked him how he thought of all the murders, he would reply that he did them personally first. Thus, when Jonathan Blake called on Hammer to look into the case of a missing person, it did appear that the author might have killed him. Hammer, twisting by habit, twisted the issue so well Blake began to suspect that it was Hammer who was in line to be murdered. But Hammer thought it was likely to be Blake. Both were dead right.
Used availability for John Newton Chance's The Murder Makers
March 1976 : UK Hardback
June 1999 : UK Paperback