Obsession, sex, and illusion are depicted in a series of parallel stories. The Lost Door opens while Kristina is being interrogated in a psychiatric hospital where she has been committed. Catherine, a young psychiatrist has been assigned by the court to discover what goes on in the deranged yet intriguing mind of this suspected murderer, haunted by ghosts and strange sexual situations. After a long confrontation, it's the mysterious Kristina who opens up the young psychiatrists mind to her own repressed desires.

Young Frenchwoman Mathilde searches for the truth about her missing fiancé, lost during World War I, and learns many unexpected things along the way. The love of her life is gone. But she refuses to believe he's gone forever — and she needs to know for sure.