The edition I read was a 1978 Ace Book paperback. The story opens with Marvin Flynn reading a classified add in the Stanhope Gazette. "Gentleman from Mars, age 43, quiet, studious, cultured, wishes to exchange bodies with similarly inclined earth gentleman. August 1 -- September 1. References exchanged. Brokers. Protected." The ad is noted to be commonplace. Marvin is described as a 31 year old, gay male (there is no further mention of Marvin's sexual orientation in the story). He is described as personable, tall, broad-shouldered, clipped black mustache, gentle brown eyes. He is described as a good mixer, healthy and intelligent. he is noted to have 12 years of college, and 4 of post graduate school. He works in a technical position in which h fluoroscopes plastic toys. He is apparently in quality control.
Chapter 2 opens with him in a soda fountain with a friend. There is some dialogue to offer a sense of the times. Marvin longs to travel. He feels trapped in Stanhope. He believes that there must be more to life. He has traveled much on earth. He wants to go extra-terrestrial. After leaving his friend, he returns home and consults an Encyclopedia regarding Mindswap. He learns: " The actual practice of Mindswap utilizes mechanical-hypnotic techniques such as induced relaxation, pinpoint fixation, and the use of a mind-positive substance, such as Williamite, as a narrow beam focuser and intensifier. Once learned, of course, you can swap without mechanical aids, usually employing sight as focus." Marvin decides to go.
Chapter 3 opens with him heading to New York City. He enters a Mindswap brokerage house, Otis, Blanders, and Klent. He meets Mr. Blanders. He engages in a qualification process. There seems to be a bit of a con in Blanders. In this chapter the reader learns of several factors related to Mindswap. One is the Reciprocal Damage Clause. In this agreement if you damage a body, your body must be equally damaged. Marvin also hears about Metaphoric Deformation. This is described as: "...Under the continued and unremitting impact of the unknown, even the analogizing faculty (described earlier as: "...We experience too much novelty; it becomes unbearable, and the mind seeks relief through the buffering process of analogizing.") can become distorted. Unable to handle the flood of data by the normal process of conceptual analogizing, the subject becomes a victim of perceptual analogizing.
This state is what we call, 'metaphoric deformation.' The process is also known as Panzaism." Panzaism is described. Don Quixote saw windmills as giants. "The reverse of this is Panzaism, which is the perception of rare entities as everyday things." (does that ring a bell!?)
Chapter 4 opens with Marvin on Mars in a Martian body. There are descriptions of his view through Martian eyes. By the end of the chapter Marvin is accused of having another being's body. He ends up with the Martian police. His trouble really begins.
Chapter 5 is an odd interlude in which a telepathic being from the planet Fulszime is described. The being is hired by the police to assist them in interrogations. The being can also predict the future. The telepath tells the policeman who hauls Marvin in that in 6 months he will commit larceny and flee the planet. By the end of the chapter the other being making claim to the Martian body, Aigeler Thrus, tells his story, Marvin tells his. The telepath finds no fault. He issues Dispossession notice to Marvin. Marvin has six hours to vacate the body. He decides to return to Earth. He cannot. Ze Kraggash is nowhere to be found.
Chapter 6 opens with Marvin making a scene in a Martian office building. He ends up at the Bureau of Detection and Apprehension, Interstellar Division. There he meets Urf Urdorf, a detective. In some comical interchanges Marvin learns that Urdorf has not solved a single case in 5 years. He as failed to solve 158 cases in a row. He reasons with Marvin that a streak like that has to end. Urdorf explains his theory that Kraggash acted out of an advanced state of obsessive projective narcissism. His description of the processes of this syndrome is uncannily convoluted. Urdorf will help Marvin but in his own style.
Chapter 7 opens with Marvin reading about his scandal in the Martian newspaper. he is quite at a loss. He meets another creature. The Erlan suggests that Marvin try the Open Market for a body, to stay alive. Marvin is referred to McHonnery.
Chapter 8 includes the dialogue between Marvin and McHonnery. McHonnery drives a hard bargain, and Marvin is desperate. He ends up taking a deal.
Chapter 9 has Marvin on the planet Melde, in a Meldan body. He is there to hunt for Ganzer eggs, and to avoid full grown Ganzers. His is a small lizard-like creature. Ganzers are large lizard-like creatures. The creatures Marvin is working for are not too informative about what a Ganzer egg looks like. They tell him you'll know when you see one.
Chapter 10 opens with Marvin still wondering what a Ganzer egg looks like. He finds one and it is large, brightly colored, mobile and -- he learns -- talkative. There is some funny dialogue between Marvin and the Ganzer egg. The egg presents with disbelief that it is being hunted. The egg is outraged, then pleading, in trying to talk Marvin out of keeping it. Along comes a full-grown Ganzer. At the end of the chapter Marvin is in the claws, and nearly the jaws of the full-grown Ganzer.
Chapter 11 opens with the scene freezing. Urf Urdorf appears in the air, Cheshire cat-like. He does not help. He, instead, asks some seemingly mundane questions about the case. He then leaves.
Chapter 12 opens with Marvin shouting for the Ganzer to wait. The Ganzer responds. He asks what for. Marvin says he doesn't want to die. The Ganzer speaks of this warning never to let a Melden speak and the danger of personalizing the job. They engage in a dialogue. They discover the set up on the planet that keeps the hunting and killing going. It is revealed that the Ganzer is also from earth, Saranac Lake specifically. The Ganzer's earth name is Otis Dagobert. As the chapter ends they realize that they are now fugitives, who will be killed on sight. They come up with a plan to visit a hermit that the Ganzer egg knows.
They meet the hermit as chapter 13 begins. There are several funny interchanges between the characters and the hermit. The hermit only speaks and understands verse. At the end of the chapter, it is revealed that the hermit has a Mindsender, of an ancient and curious design. He was making a healthy fortune smuggling refugees.
At the beginning of chapter 14 Dagobert is sent off to a planet to be a dental assistant because the hermit decided that he had a streak of sadism. Marvin, on the other hand, decided he was cut out to be a victim. Marvin is sent off to planet Celsus V.
Chapter 15 opens with a character Marduk on this planet. He is given a gift of a snout ring (very fashionable) except it is ticking. On Celsus V one does not return a gift. So Marduk, not knowing if the ticking was a real bomb or just a warning from political rivals, swaps his way off the planet. Marvin is in his place. Mardukk Kras has left a letter for Marvin. He warns Marvin not to remove the snout ring, with the caution that it might explode. Marvin gets acquainted with his surroundings as chapter 15 ends.
Marvin has a sense that things are getting strange as chapter 16 begins. The scene seems to have shifted to southwestern imagery from planet earth. A character, a saddlebum, explains to him that he's "merely" changed his system of "metaphoric reference". The character goes on to say that he doesn't blame him, and that the animal-insect comparisons were "dreary". The character, shortly after, tells Marvin that he is Necessity personified, or else Marvin would have to remember the Theory of Metaphoric Deformation on his own. Marvin and the saddlebum end up on a saloon. Marvin is harassed by a woman there.
As chapter 17 begins, he comes to the realization that the saddlebum is in fact a large beetle. Marvin is despondent. He comes to a bridge, contemplates suicide. He is getting ready to jump, when another being seems to be doing the same thing. He rescues the other being who turns out to be female as the chapter ends.
They open chapter 18 together in a booth of a restaurant. They have a crazy conversation full of cliché lines from old movies. He learns that her name is Cathy. Another character is introduced who refers to himself as Juan Valdez. He claims to be an investigator.
As 19 begins Juan Valdez persuades Marvin to walk with him to his home town. He speaks of the Theory of Searches, in which no object can truly be lost. They are walking toward Juan Valdez' home as chapter 20 begins.
Valdez leads him to a Location Point (theory of searches), and they wait for Cathy. After an hour a figure appears on the horizon. It is Marvin's uncle Max. The converse. Max moves on. Soon after, Marvin's mother comes by. Later his father does. As the chapter goes on, there is more talk of the theory of searches. As the chapter ends Cathy appears.
Chapter 22 is a nice little chapter. By the end of it, Cathy is gone. Chapter 23, there is a strange bit about Loss of the Beloved. Chapters 24 - 30 introduces a whole new set of characters and story line. The story line is a palace intrigue story like a Victor Hugo or Alexander Dumas story. Marvin plays a dashing swordsman. By the end of chapter 30, Marvin's adversary is revealed as Ze Kraggash. There is a scene in which Marvin looks into his own face. Another of the characters in this subplot turns out to be Urf Urdorf, doing his job.
Chapters 31 and 32 have some details about the Twisted World. Marvin winds up in his own body at the end of Chapter 32. The story ends in Chapter 33 with Marvin back on earth, seemingly in his home town of Stanhope. From the description of the last few paragraphs it remains unclear if Marvin has ever returned from the twisted world.