The book series is set in dreary post apocalyptic world where everything from your neighbours, mutants of all varieties, war lords, bandits, cults, cannibals, lost tech, and even the weather is trying to kill you. It is all set against a back drop alternate time line where the cold war went hot. The US and the USSR destroyed each other and the world in a flurry of nuclear, biological, and chemical weapons applied en masse. The resulting hell scape in the US is called The Deathlands. It is a mix of environments often punctuated by unusual or hostile weather and terrain features. Much of the wild life that is present comes in two general flavors. Normal but hardened by a hard life surviving the harsh conditions and mutant monster creatures who are often deformed massive monsters with unparalleled aggression and violent behavior. To add to the harsh conditions the human animal is perhaps the worst and many groups are either mentally unstable and/or corrupt or notably mutated in various ways.
The Main characters originally are from a band Operating under a man simply called The Trader. It is roving band of heavily armed mercenary like merchants roaming the waste land cashing a profit selling tech from scavenged pre-war caches of technology and supplies that survived the apocalypse and can still be found from time to time. Some of the traders earlier finds come back to bite them in the ass by the end of the first book leaving a scant few survivors. The band quickly picks up new members and struggles to escape the region after destroying the local power structure run by a typical corrupt war lord often referred to as a Baron.
This leads the group to discover an abandoned technology in a old government bunker that can teleport them with an experimental technology to distant places in other bunkers. The plot becomes strange and convoluted at times across the stories including an example of time travel where people are pulled from different times or pushed forward into others forcefully. The effect is not pretty or healthy for the mind and body.
The books are heavy on blood and guts and graphic depictions of torture and sex which are often borderline acceptable. Later examples of the books have different authors and tone down some of the worst aspects of graphic depictions.