The DNA Cowboys series by Mick Farren is a group of four novels, The Quest of the DNA Cowboys (1976), Synaptic Manhunt (1976), The Neural Atrocity (1977) and The Last Stand of the DNA Cowboys (1989), the latter forming a coda to the saga. Although sharing the sensibilities and themes of New Wave sf, there is little of the stylistic experimentation that characterized many novels of the period. The books are mistakenly listed in the ISFDB as the "Jeb Stuart Ho" series, although Ho only appears in two of the books (Synaptic Manhunt & The Neural Atrocity).
The eponymous DNA Cowboys are Billy Oblivion, Reave Mekonta, and their on-again, off-again companion The Minstrel Boy, an experienced traveler who has the rare talent of being able to navigate his way through the nothings (as we later learn this is thanks to a lizard brain implant). The nothings are the psychedelic chaos that separates the fragmented human communities that are all that remains of a world where reality has broken down. After some adventures (including being drafted into Sauron's army) Billy and Reave eventually end up in the company of the patrician libertine AA Catto, a woman whose emotional immaturity is reflected in her permanently adolescent body.
Things really pick up in the second and third novels, when the assassin monk Jeb Stuart Ho enters the picture. He's been dispatched by his order to bump off Catto, and he strong-arms Minstrel Boy into acting as his guide. Ho soon runs afoul of the policeman, Bannion, and Catto, Reave in tow, gets wind of his plans as does Billy. The chase is on and it soon becomes clear that the reason Catto is such a danger is that her egomania has become a full-blown Napoleon complex. She's determined to wreak havoc in her mad pursuit of world domination.
Simultaneously with all of this we follow the progress of She/They, a tripartite female entity that holds humanity in little regard.
The fourth book tells a similar tale as the DNA Cowboys, accidentally reunited, reluctantly take a stand against the warlord Vlad Baptiste and his cohorts as he lays waste to the remaining pockets of humanity in the course of his fanatical vendetta against the haughty Metaphysicians.
The DNA Cowboy books are best seen in their context as a part of 1970's pop-culture. Reading them is like watching a Ralph Bakshi movie, full of swirling colors and counter-culture allusions. It's a world where Kwai Chang Caine rubs shoulders with Kojak and Elvis finds himself out of his element. The references range from The Lord of the Rings, TV Westerns, Dune to rock and roll (including Farren's own songs). While competently written, these aren't Farren's best books (David Langford was unsparing in his review of them). The fourth novel finds Farren a more assured writer, and involves a bit of retconning. It also seems to have been written at a time when his fascination with military history was running high. It provides a satisfactory conclusion to the tale of the DNA Cowboys allowing them to find either apotheosis or go out in a blaze of glory. If you want to find out which they choose you'll have to take a hit of cyclatrol and follow the DNA Cowboys yourself.