Directed by Otto Preminger and starring Carol Lynley, Keir Dullea, and Laurence Olivier, Bunny Lake Is Missing follows a mother searching for her daughter who disappears from a London nursery, only to face growing uncertainty about whether the child ever existed. Adapted from Evelyn Piper’s novel, the film centers on investigation, perception, and psychological uncertainty surrounding the disappearance.

Från IMDB:
A woman reports that her young daughter is missing, but there seems to be no evidence that she ever existed.