On a fishing trip with his parents, young Charlie reels in a black boot from the grimy depth of the sea. Soon after a strange figure lurking in the shadows attempts to lay its hands on something that will tear the family apart.

As musical theatre superstar Valerie Broom juggles her career, motherhood, and an ambitious understudy, the arrival of live-in nanny Grace disrupts their family dynamics, exposing a disturbing secret.