The pairing of Hammer horror stalwarts Peter Cushing and Christopher Lee doesn't always guarantee a good time -- see Night of the Big Heat (1967) for proof of that. This film - the one and only from Lee's own Charlemagne Productions - isn't the pair's best work together, but it is far from the disaster that some would have us believe.
Lee plays Colonel Bingham, who teams up with eminent pathologist Sir Mark Ashley (Cushing) to investigate the suspicious deaths of several elderly members of the Van Traylen Trust, who fund the Inver House orphanage, home to Mary Valley (Gwyneth Strong), survivor of a mysterious bus crash that claimed the lives of three of the trustees. Prime suspect is Anna Harb (Diana Dors), Mary's estranged mother, ex-prostitute and triple murderess, who is so desperate to be reunited with her daughter that she would kill again if necessary. Mary is sent to back to the orphanage in Scotland for her own safety, but Harb follows, with Bingham and Ashley not far behind; what they discover at Inver House is far more terrible than they could have imagined.
Lee and Cushing put in commendable performances, attacking their roles with gusto and gravitas; in contrast, Dors overacts with ham to spare, her eccentric turn providing the film with a sense of fun. Director Peter Sasdy (Taste The Blood Of Dracula, Hands Of The Ripper) keeps the pace snappy and the mystery intriguing, delivering a surprising Psycho-style death of a major character a third of the way through, a terrific explosion to jolt the viewer out of their seat, the grisly discovery of a mutilated seven year old, and a shocking conclusion that has more than a touch of The Wicker Man about it (beyond Lee's presence and the remote Scottish location).