After the first human contact with the Siwannese ended in a mass suicide, the Terran government made a law that no further contact with sentient aliens would be allowed. But since their own planet was overcrowed, they looked to colonize Doona--until they found the Hrubbans. Their choice was simple but dangerous. They could kill the cat-like Hrubbans, or for the first time in history, learn to to coexist with an alien race....