In June 1964, South Africa's most visible antiapartheid activists were sentenced to life in prison in the infamous Rivonia Trial. These men included Nelson Mandela, Walter Sisulu, Denis Goldberg, and, the youngest of the group, Ahmed Kathrada -- or "Kathy," as he was called by his friends. Kathrada spent the better part of the next three decades imprisoned on Robben Island, enduring lengthy stays in solitary confinement, frequent abuse from the guards,...