When an unknown entity takes control of the science station orbiting Mendel, Corree goes aboard and discovers a sinister plot to overthrow the Federation government. The entity wants Corin, the young clone of the scientist Windemere, the man who created the Mendelian mutants. Corree takes Corin's place by mutating to look like the clone. She finds a terrible plot to destroy the leaders of the Federation, but to destroy all non-humans in the galaxy.