Reeling from her husband's death and best friend's dementia diagnosis, seventy-six-year-old Linda Davidson is feeling lost and alone. Her beloved daughter Kleo and son-in-law Mick move into her house to keep her company, but the constant bickering quickly turns their presence into just another thing on Linda's long list of worries.

Eager to escape the tension at home, Linda goes to visit her friend at Legacy Place, a Memory Care facility for the elderly, where she meets Jenny Cooper, a ninety-two-year-old dementia patient who makes a shocking confession: she kills people.

Linda dismisses the so-called "secret" as the confusion of an ailing mind, but Jenny seems strangely lucid over the course of their visits as she tells Linda about her many victims--mostly men who hurt her. Then, a fellow patient at Legacy Place dies. Everyone else sees the natural death of an old, sick man, but Linda can't help but wonder: is there any chance Jenny's telling the truth?