Finalist for the 2010 Prix Aurora Award for best Canadian science fiction or fantasy novel in English.
The publisher’s blurb:
Marseguro, a water world far from Earth, is home to a colony of humans and the Selkies, a water-dwelling race created from modified human DNA. For seventy years the colony has lived in peace. Then Earth discovers Marseguro, and a strike force is sent to eradicate this “abomination.” But Marseguro has created a genetically tailored plague to use against Earth’s Holy Warriors. With the enemy defeated, the people of Marseguro feel they are safe. But Chris Keating, the traitor who signaled Marseguro’s location to the Holy Warriors, has fled to Earth, unknowingly carrying the deadly plague within him. The people of Marseguro feel they must send a ship to Earth with a life-saving vaccine. Only time will tell what awaits them when they reach their destination.