The plot alternates between two points of view, that of Dr. Juna Saari, a xenobiologist member of a human Survey crew who unintentionally strand her on the planet of the Tendu, intelligent amphibians with exquisite physiological control, and Anito, a Tendu who helps with Juna's adaptation and ensures her survival.
In order to rescue Juna, the Tendu extensively modify her biology, adapting her to the otherwise toxic atmosphere and allowing her to live among them.
When Juna is rescued at last by a returning Survey mission, re-entry into human society proves as difficult for her as adapting to Tendu ways.
When the Tendu, with the extensive inner physiological control, prove able not only to heal the human team member Dr. Wu after a heart-attack, but clear out the cholesterol from his arteries and restore him to something approaching youth, the former suspicion and distrust between species begins to dissolve.
Ultimately, Moki and Ukatonen opt to return with Juna and the rest of the Survey team to Earth, setting up the plot for the sequel.