They all thought he was gone. But he was alive and trapped inside his own body for ten years.

In January 1988 Martin Pistorius, aged twelve, fell inexplicably sick. First he lost his voice and stopped eating. Then he slept constantly and shunned human contact. Doctors were mystified. Within eighteen months he was mute and wheelchair-bound. Martin's parents were told an unknown degenerative disease left him with the mind of a baby and less than two years to live.

Martin was moved to care centers for severely disabled children. The stress and heartache shook his parents' marriage and...