Joe and Wanda found each other in midlife. Deeply in love, they'd just bought their new home when Joe's diagnosis of early-onset Alzheimer's changed everything. "Until death do us part" took on an immediate, deeply personal meaning.

"White Knight "recounts the couple's four-year journey through Alzheimer's, a journey that ended with Joe's death. Initially Wanda, like many caregivers, mourned for the husband she used to have, teetering between despair and panic while she adapted to the couple's new reality.

Then something wonderful happened. Wanda came to a realization that helped her...