Can interspecies diplomacy begin in the womb? Humans have lived on Tofarn, planet of creeks and rivers, for seventy years, but they still don't understand the Tofa. The Tofa are an enigma, from their featureless faces to the four arms that sometimes seem to be five. They take arbitrary umbrage at the simplest human activities, while annoying their human neighbors in seemingly pointless ways. The next infuriating, inexplicable incident may explode into war. Scientist Mara Cadell's radical proposal: that host mothers carry fraternal twins, human and Tofa, in the hope that the bond between twins can bridge the gap between species. Mara knows about the bond between twins: her own twin, Levi, died in utero, but she has secretly kept him alive in her mind as companion and collaborator. Mara succeeds in obtaining governmental backing for her project – but both the human and Tofa establishments have their own agendas. Mara must shepherd the Twin-Bred through dangers she anticipated and others that even the canny Levi could not foresee. Will the Twin-Bred bring peace, war, or something else entirely?...

Scientist Mara Cadell created the Twin-Bred—pairs of fraternal twins, one human and one Tofa—to bridge the profound and dangerous gap between the human colonists on Tofarn and the indigenous Tofa. Unexpectedly, it is the Tofa host mothers who now claim the capacity to bring peace between the two. The Twin-Bred themselves have been forced to abandon their mission and their planet, in the hope of finding a less hostile home. Only one pair remain behind, seeking to build new and separate lives with their own kind. But Mara and the Twin-Bred should know by now that plans provide little protection. New challenges are in store for all the Twin-Bred, and for those whose lives they touch.