Wil McCarthy combines two branches of speculative thinking -- space travel and biotechnology -- to create a chilling and entirely believable future, as Bloom pits humankind against an enemy of its own creation, now rampantly out of control. In the late 21st century, manmade self-replicating organisms, smaller than the tiniest bacteria, have mutated and swept across the planet, spreading so swiftly that there is no time to do anything but flee and watch the Earth -- and then the whole inner Solar System -- literally consumed and incorporated into the entity known as the Mycosystem. A few years later, the remnants of humanity cling to existence in the asteroid belt and the moons of Jupiter, fighting off the spread of the Mycosystem while they work feverishly to build a starship to carry them to safety. Then they discover that the Mycosystem is mutating in a way which may soon endanger them again. The only way to be sure is for volunteers to journey into the heart of the Mycosystem, a realm from which no one has ever returned.