A Scotland Yard detective is investigating a string of robberies and a murder, and the information he uncovers leads him to the estate of a wealthy but strange English family, who share their mansion with a group of nuns. The detective comes to suspect that neither the family nor the nuns is quite what they seem to be.
The Trygon Factor is a 1966 British-West German crime film directed by Cyril Frankel and starring Stewart Granger, Susan Hampshire and Robert Morley. It is based on the 1917 Edgar Wallace novel Kate Plus Ten.
