Dirk Gently, who calls himself a "holistic detective", has happened upon what he thinks is a rather comfortable situation. A wealthy man in the record industry has retained him, spinning a story about being stalked by a seven-foot-tall, green-eyed, scythe-wielding monster. Dirk pretends to understand the man's ravings involving potatoes and a contract signed in blood coming due; when in reality, Dirk is musing about what he might do if he actually receives payment for his "services" – such as getting rid of his refrigerator, which is so filthy inside that it has become the centrepiece of a showdown between himself and his cleaning woman. The seriousness of his client's claims becomes clear when Dirk arrives several hours late for an appointment to find a swarm of police around his client's estate. The aforementioned client is found in a sealed and heavily barricaded room, his head neatly removed several feet from his body and rotating on a turntable. While at his recently deceased client's house, he discovers that his client had a son. However, after Dirk disconnects the television set the boy had been watching, the boy promptly breaks Dirk's nose.
Nearly incapacitated by guilt, Dirk resolves to take his now-late client's wild claims seriously. During his investigation, Gently encounters exploding airport check-in counters, the gods of Norse mythology, insulting horoscopes, a sinister nursing home, a rhinophagiceagle, an I Chingcalculator (to which everything calculated above the value of 4 is apparently 'a suffusion of yellow'), an omnipotent being who gives his powers to a lawyer and an advertising executive in exchange for clean linen, and an attractive American woman who gets angry when she can't get pizzadelivered in London.