This is the story of the adventures of an interstellar ship and its crew, each of whom is required to provide three areas of expertise. MDs are mono-specialist, so there are no medical doctors on board.
Eventually they discover a perfect planet which is peculiar only in that its atmosphere contains three percent Xenon. xenon has no effect on humans at a level of three percent, but is an "ideal" anaesthetic at high concentration.
At first the planet seems devoid of sentient life; but soon the humans discover that it has already been colonized by the gigantic, insectform, aggressive and predatory, female-dominant Xcrath and their diminutive, apparently subjugate, mutant cousins, the Xcarianth.
Throughout most of the year, The Xcrath are tranquilized by a high ambient Xenon. However for one month during Winter, when Xenon freezes at the poles and its atmospheric concentration falls, their natural aggression comes to the fore.
It turns out that both Xcrath and Xcarianth are plagued by mutations of varying severity: The humans devise a simple surgical solution to the most debilitating of these, thus securing the loyalty of one group and incurring the enmity of another.
The fragile peace is interrupted by a surprising development, which threatens both human and native existence. Xcrath and human responses to this new situation are examined, as each group comes to grips with the new reality.
The plot is innovative, the narrative crisp. The author's surgical background adds an unusual element of medical intrigue and a dash of humour as the Xcraths' disabilities are explored. The tale is absorbing and the tempo quick. This is first-rate Science Fiction.