On the day a priest came to her hospital bed and prayed over her withered body, Diana Abad would not have believed good fortune awaited. Or seemed to be, until one day her back started to ache and another day her legs swelled. She had her blood tested and learned her white-cell count was absurdly high. Leukemia, her doctor said. Without a bone-marrow transplant, she would be dead in nine months. David Mason would not have believed in 1990 that by checking a box on a Navy form he would set in motion the chain of events that led him...