Traumatized by the global war that killed their home planet, surviving people of Baas--an eight-limbed, all-female species--adopt an orphaned prehistoric girl (Clover) while on Earth collecting plants for their new planet. Traveling in a dimension they call "Slow Time", the Baasians return to Earth every several centuries, adopting other outcast humans. But a major increase in human technology disrupts their latest visit, and they struggle to stay hidden from view. Stranded in Forest Park, Portland, Oregon, the desperate landing party rescues homeless science teacher Charlie Schwitters from two muggers. Charlie finds himself helping three Baasians--Toochla, Xashan and Drasher--Clover (who bonds immediately with him), a tough ancient Greek philosopher, a pre-Islam Arabic woman, a Celtic midwife, a refugee from the French Revolution, and a crucified Palestinian Jew deal with a confusing modern society. But word soon gets out about the unusual weapon that the Baasians used against the muggers, and the landing party find themselves at the center of a potential interplanetary war.