The basis for Lifetime's Don't Trust the Girl's Upstairs.

After taking in her estranged niece, a woman fears for her family's lives, in this domestic thriller by the author of Reese's Book Club pick The Last Mrs. Parrish.

Things have been different since Serena came to stay . . .

Ashley Bowers is shocked by the sudden death of her sister, whom she hasn't seen or heard from in years. Grieving for the bond they once shared and wallowing in the knowledge that any chance of reconciliation is gone forever is one thing. Welcoming her sister's thirteen-year-old daughter—a girl Ashley has never even met—into the home she shares with her husband and two children is another.

Ashley hopes Serena will blend in seamlessly with her family and their peaceful life in Maryland once they've both had a chance to process their loss. But as days become weeks, personalities clash and troubling incidents turn the Bowers residence into a whirlwind of accusation, denial, and fear.

It starts small: missing items, the dog inexplicably locked outside all night. But when the safety of her own children is threatened, Ashley starts to wonder if the tragedies in Serena's past are unfortunate coincidences or something more sinister. Is Ashley's orphaned niece simply acting out after the tragic passing of both her parents? Or is something far more dangerous going on under her own roof?

Dark secrets and unexpected twists will keep you guessing until the very end in My Sister's Daughter, a thrilling novella that undoes puzzles of the past from New York Times–bestselling author Liv Constantine.