Immediately before his death, the wealthy patriarch of the Darkwood Manor modifies his will, leaving his entire fortune to his granddaughter Gwendoline (Karin Dor). This upsets the plans of the dead man's greedy relatives, which includes Patricia (Ilse Steppat), who needs the money to finance the girl's school she operates at the manor, brother Richard (Siegfried Lowitz), and her son William (Dieter Eppler). William is the kind of fellow you wouldn't want anywhere near your daughter, and Richard doesn't balk at killing the family lawyer by forcing his car off the road, and stealing the will.
Into this den of malefactors comes Gwendoline, unaware of the events swirling around her. The malice continues: A student is murdered; a mysterious monk stalks the manor, strangling people with a whip; and Gwendoline is sexually harassed by William, whose earlier murder of a school girl was hushed-up by the family. Mr. Short, an oddball character sequestered in the manor's attic, raises carrier pigeons and has made plaster life masks of locals who recently died.
Scotland Yard inspector Bratt (Harald Leipnitz) attempts to clarify the mystery when the monk kills one of his men. After some school girls disappear without trace, he tracks one of Mr. Short's pigeons and discovers a ring of white slave traders, led by the monk. Gwendoline is abducted and brought to Richard, who explains the history of her grandfather's will and attempts to blackmail her. He is interrupted and strangled by the monk, who then dies from his wounds. Bratt arrives too late to do anything other than reveal the monk's identity.
Filmed as part of the Edgar Wallace series of krimis produced by Berlin's Rialto Films, this mildly entertaining thriller was the last black-and-white film of the successful crime series. It was very successful during its initial release, and holds up well more than 30 years later.
Director Harald Reinl, then husband of the film's star Karin Dor, moves things at a fast pace. Though it's not too difficult to guess which character plays the monk, there are numerous red herrings and distractions, and THE SINISTER MONK boasts a high body count overall. The film's "deadly accoutrements" include the whip, which is modified to break one's neck in an instant, and a water pistol that fires sulfuric acid.
The movie is an adaptation of Edgar Wallace's novel "The Terror," which had previously been offered as a stage play in London in the 1920s, followed by three forgotten film versions in 1928, 1934 (as RETURN OF THE TERROR), and 1938. THE SINISTER MONK was itself remade two years later, as DER MÖNCH MIT DER PEITSCHE (1967), directed by Alfred Vohrer.
