What the Peeper Saw (also known as Night Hair Child, Diabolica Malicia, Der Zeuge Hinter Der Wand, What the Peeper Saw and La Tua Presenza Nuda) is a 1972 thriller film directed by James Kelley and Andrea Bianchi and starring Mark Lester, Britt Ekland, Hardy Krüger and Lilli Palmer.

Three months into their marriage, Marcus returns home from boarding school, two weeks before term finals.

Marcus replied that he took a thousand pesos from his father's study, prompting Elise into thinking that he stole the money.

She later tries to warm up to Marcus and asks him about his early return from school, to which he replies that a chickenpox epidemic broke out there.

She finds the shredded remains of a letter Marcus received from the mail earlier which he claimed to have come from his school book club.

A shocked Elise later tells Paul about this, who admits Marcus' mental disorientation after his mother's death.

A shocked Elise then demands answers from Paul, who reluctantly tells her that the house belonged to them before Sarah died.

She runs to the attic where she finds a hole was dug underneath the floorboards so that she and Paul can be spied upon.

A couple of days later, Paul finds their family dog floating dead in the pool.

By using reverse psychology in a lengthy inquiry, Viorne makes her doubt her claims as she had no proof.

Elise denies the claims and keeps telling that she was made to strip by Marcus in exchange of his confession, but Viorne doesn't believe her.

Elise, now being accused of sexually assaulting a minor, becomes mentally unstable and decides to kill Marcus in his sleep.

Despite brief glimpses of Lilli Palmer as a psychiatrist, the psychodynamics of the situation are barely explored, and the audience is basically required to accept that Marcus has somehow become a fully developed psychopath without exhibiting any symptoms at all to his unsuspecting parents.

Only Harry Andrews' appearance as a headmaster in the brief English sequences provides welcome relief from the unlikely family constellation which the film pretends to examine.