From the back cover:
"Called to the end of time by a being they knew only as The Face of Ea, four adventurers from the twentieth century faced a power that not even the super-science of that era could meet -- the nekron, negative matter, negative force, ultimate destruction for everything it touched. It seemed hopeless to expect them to win this battle for the fate of the universe -- but between them they had a power they themselves could not suspect."
A series of strange murders and a story assignment sweep reporter Jerry Cortland into a wild science fiction ride, full of split-mind possessions, cloning, and time and space travel (often in a smash cut blink of the eye), where he, along with three other humans, must battle the deadly, advancing void of the nekron, in order to save not only Earth, but past/future alien civilizations.
This story was initially confusing to me -- Kuttner often favors fast, one-sentence transitions to convey complex theories and twists, alternating/mind-sharing personalities, as well as space and time travel. Once I got into the blunt, choppy rhythm of the story though, it was an exhilarating blast-read.
This is not recommended for people who want everthing explained to them; this is a action- and abstraction-packed work, from an author who eschews traditional transitions and science fiction clichés.
The Time Axis is fun, vagaric, with a smart-minded b-movie feel to it. Check it out.