EDITOR’S NOTE: The Trygon Factor was on the CBS Late Movie on January 23, 1973 and January 2, 1974.

Das Geheimnis der weißen Nonne (Mystery of the White Nun) is known in the U.S. as The Trygon Factor and is based on Edgar Wallace’s book Kate Plus Ten.

Inspector Cooper-Smith (Stewart Granger) is on the hunt for a group of thieves who have been stealing various unconnected goods. His investigation leads him to the country manor of the Emberdays, a respectable English family. The mistress of the house, Livia (Cathleen Nesbitt), and Sister General (Brigitte Horney) and the nuns living in her home, are all suspects. Could they be behind the thefts to save the family fortune? The plot thickens when Inspector Thompson (Allan Cuthbertson) is murdered at Emberday Abbey. The Emberday children, Trudy (Susan Hampshire) and Luke (James Culliford), also come under suspicion.

The Trygon Factor leans more towards the Eurospy genre than the nascent Giallo, a style of Italian thriller, as the Krimi cycle of films began to slow down. The Eurospy genre is characterized by its focus on espionage and action, which is evident in the film’s plot and action sequences. Director Cyril Frankel, known for his work on UFO, The Avengers and Return of the Saint, brings his expertise to the film. The script was written by Derry Quinn (Young, Willing and Eager) and Stanley Munro.

One of the most intriguing scenes in the film features a gang member in a striking yellow suit of armor, wielding a gigantic gatling gun to burst through a bank wall. This unique sequence is only topped by the unexpected moment when Stewart Granger’s character punches a nun right in the face.