In 1958, Anna Jurin accepts a job as a housekeeper of Saint Ange, a rusty and isolated orphanage located in the French Alps and owned by Madam Francard.

Other than Anna, the orphanage is now populated by only two people: the long-time cook Helenka and an adult orphan, Judith, who suffers from a mental disability and claims that there are other, unseen, children in the location.

However, Helenka dismisses her worries as mere hallucinations, especially after she learns that Anna is pregnant due to a gang rape, a fact that she tries to hide at first.

She gains the trust of Judith by befriending and calming her when her kittens are apparently drowned by Helenka, enough for her to disclose that the children inhabit an area somewhere behind a mirror in the bathroom, revealed to be an abandoned dormitory.

Judith realizes that the children had really died and begs Anna to stop searching, but the latter insists on continuing and boards an elevator heading to the underground.

The star in fact wore a prosthetic pregnancy for the shoot and spoke of the hard bodily work and physical discomfort this entailed: "We shot scenes in stifling heat, with my hair sticking to me, false blood on my face, and the latex stomach melting.