Wrapping up the trilogy of the talky Voyagers (1981) and the mediocre Voyagers II(1985), about messiah Keith Stoner and his alien-inspired mission to save humanity from itself. Jo Camarata, Stoner's wife and boss of the multinational Vanguard Industries, faces a power struggle led by the most dangerous board-member, fanatical Li-Po Hsen. Stoner, meanwhile--his body occupied by virus-sized alien machines ("nanotechnology") giving him perfect health, various superhuman powers, and an empathic alien presence ("star brother") in his head--unobtrusively wanders the globe, aiding the Good and spreading nanotechnology to those who can handle it without going mad. But part of Hsen's plot involves capturing Stoner and dissecting him (literally) to learn the source of his powers. Also, a traitor on Jo's staff reports everything to Hsen. And a vengeful Vanguard renegade has released a nanotechnology disease-machine that agonizingly chews people to pieces within hours. So, Jo and Stoner must defeat Hsen and spread the good nanotechnology before the disease-machine kills everyone on Earth. Still choppy and overpopulated, and preachy at times--but at last Bova has really thought about his aliens and their abilities. Much the best of the three.