Five years after the departure of the Dark from Darwath strange occurences begin to develop in the Vale of Renweth. There are geological upheavals and an increasing amount of slunch - a heavy, inedible, juiceless fungus. Cave bears, woolly mammoths and sabretooths seem to be flocking to the area. Even stranger are the sightings of thaght'n - creatures who possess a kind of magic which even magician Rudy Solis cannot defeat or deceive. Thus as Gil, who crossed the void from present day California, and her lover, the wizard Ingold, return to the Keep from the flooded delta city of Penambra, they realize that something is desperately wrong...

Something, somewhere, is attempting to terraform the world by the use of magic: to accelerate the rate of chilling until the temperature reaches the point that it - whatever it is - finds comfortable...