Mute is science fantasy of mutation and psi: special mental powers. The protagonist, Knot, is a double mutant: he has a physical deformity, and the psi power to make others forget him. He’s satisfied with his life--until the lovely Finesse walks into his life to recruit him for a dangerous galactic mission. She is aided by two small animal mutants: a telepathic weasel and a clairvoyant crab. Knot tries to resist, aided by his psi, but the woman’s beauty and the animals’ powers doom him to a phenomenal adventure. The prior edition was cut; this is the complete version.
Chthon was Piers Anthony’s first published novel in 1967, written over the course of seven years. He started it when he was in the US Army, so it has a long prison sequence that is reminiscent of that experience, being dark and grim. It features Aton Five, a space man who commits the crime of falling in love with the dangerous alluring Minionette and is therefore condemned to death in the subterranean prison of Chthon. It uses flashbacks to show how he came to know the Minionette, and flashforwards to show how he dealt with her after his escape from prison. The author regards this as perhaps the most intricately structured novel the science fantasy genre has seen. It was a contender for awards, but not a winner.
Phthor is the sequel to Chthon, less intricately structured and less complicated in plot, but still quite dark and ugly in theme and detail. Rather than flashbacks and flashforwards, it has a Y outline, with the stem the initial story and the ends alternate futures, neither of which is acceptable to Aton’s son Arlo. Arlo has his own encounter with a Minionette, and naturally destruction is upon him and all with whom he associates. Write/editor Charles Platt was so impressed with the chthonic setting that he wrote two additional sequels, Plasm and Soma, which are even darker and grimmer.