Raine Moss has memory problems, but when her sister Dorsey suggests a doctor's visit, Raine's husband, Hartley, laughs it off as just part of his wife's zany personality. But following an enigmatic trip to the Bahamas with her husband, Raine's mental condition takes a dark turn, and it is no longer anything to laugh about. Dorsey lives in Taos, New Mexico, only an hour from her sister in Santa Fe. After Dorsey pressures Hartley to seek medical attention, he relents, and at 53, Raine is diagnosed with early-onset Alzheimer's. At that point, Hartley seizes control of his wife's finances and health care by declaring her legally incompetent.

Dorsey grows concerned as her sister becomes depressed and withdrawn. Finally, one afternoon, she makes a surprise visit to Raine's house. Hartley is away, and the housekeeper takes Dorsey to her sister's bedroom. Raine is napping, but Dorsey sees that Raine has gone from an erstwhile beauty queen to a snoring exoskeleton, someone Dorsey barely recognizes. She needs to learn more about Raine's domineering husband and accesses his computer. Hartley has left a window open, and when Dorsey taps a key, BOOM! What she finds is horrifying, and her life changes forever. Now she is compelled to fight for her sister's sanity and freedom from a monster.

When Bogart Dudley dies suddenly, Raine inherits the family's ancestral home in the North Georgia Mountains. But Hartley, a gambling addict, is furious she didn't inherit any money. As a result, his plans to settle debts were thwarted, forcing him to devise another, more sinister way to find some quick cash. However, his blackmail scheme unearths some secrets that will cost him dearly.

Dorsey, her sister Margaret, and Tessa, Raine's daughter, cajole Hartley into moving Raine to a memory care unit at Waterhaven, a posh senior living facility in Atlanta. Here, Raine reacquaints with her cousin, Mary Etta DeRenne, who has created and endowed a magnificent garden for the residents. At 43, Etta is Waterhaven's youngest resident and suffers from a malady that requires her to be near a hospital. The two women couldn't be more opposite: Raine, a former debutante, and Etta, home-schooled due to merciless teasing over a physical deformity.

Nevertheless, Raine and Etta bond, and when blind Dr. Broadmoor joins them, an unconventional love story is born. Dementia, addiction, trafficking, and abuse are themes scattered throughout the story, but inside Etta's garden, we learn there are miracles, even though some are bittersweet.