Newly appointed xenologist Konstantin Kratov finds himself right in the heart of the Galactic Brotherhood—on the artificial planet Sfazis. He takes part in xenological missions in different ends of the universe. One fine moment, fate brings him together again with a radiogen—but this time with a different, non-human one. A sinister device caused a humanitarian catastrophe: on the planet Cerus I, almost all species of living beings became intelligent in defiance of all natural laws, and started destroying one another… This incident only strengthens Kratov’s belief in the deadly nature of such experiments.