When Madeline Was Young/Jane Hamilton

Shortly after Aaron Maciver married Madeline, his wife suffered a debilitating brain injury that left her with mental capacity of a small child. Years later, Aaron remarries, but he and his new wife, Julia, refuse to leave Madeline stranded. They take her into their suburban Chicago home, caring for her and accepting her into their lives almost as a beloved child; during nights of high anxiety, she even shares their marriage bed. Decades later, their son, Mac, reflects on this unusual, even eerie ménage, pondering its effects on his parents and himself.

This was thoroughly engrossing. The subject matter so unique. I also loved Hamilton's Map of the World.