Small World — Martin Suter

At first they thought Konrad's absentmindedness was due to his drinking. For years, he had been a benign parasite on the Koch family. But when their villa burns down because of Konrad's forgetfulness, Elvira Senn, matriarch of the Koch family, puts him on a strict regime. No longer allowed his daily tipple, Konrad recovers and even falls in love. But then his condition deteriorates, and Alzheimer's takes hold. As he loses his present, he regains his distant past, and this is what Elvira fears the most. As they wait for him to rewind to the crucial moment, his life is in danger from far more than a debilitating disease.