An anguished philosophy professor watches his dying mother's measured steps into the mysterious depths of neurological illness: the misplaced glasses, kitchen catastrophes, and anecdotes told over and over to a family overcome with fearful sympathy. His strenuous efforts to make sense of his mother's suffering lead him to learn all he can about her illness, renewing contact with his neurologist brother in the process. But medical science can do nothing to ease loss, and genetics now routinely predicts destinies that medicine is powerless to avert.