Die blaue Hand (1967)

Dave Emerson, one of the four sons of the criminal Earl of Emerson, who fled to America, stands trial for the murder of the gardener Edward Amery. Using a medical report by the asylum doctor Dr. Albert Mangrove, the family’s lawyer, Lionel Douglas, succeeds in having Dave committed indefinitely to Mangrove’s asylum on the grounds of “complete insanity.” Shortly afterward, an unknown person helps Dave escape from the clinic. A nurse is murdered under mysterious circumstances. A guard and a watchdog, who pursued Dave as he fled toward his parents’ castle, Gentry, are killed by a hooded figure wielding a blue iron hand. At the castle, Dave nearly encounters his twin brother Richard, who looks exactly like him and disappears without a trace that same evening. When Inspector Craig and Scotland Yard chief Sir John arrive at Gentry Castle to question everyone there, Dave promptly assumes his brother Richard’s identity. At first, neither the investigators nor Dave’s siblings Robert, Charles, and Myrna, nor their stepmother, Lady Emerson, notice. Craig searches Dave’s room and finds strange things, including a reference to the “Blue Hand,” a historical murder weapon. Inspector Craig realizes that Richard is actually Dave. Just then, Myrna narrowly escapes an attack by the Blue Hand. Dave manages to convince the inspector and Sir John of his innocence. The next day, Reynolds, a guard from Mangrove’s asylum who is posing as Dave, lures Myrna to the Petit Maxim club. Robert Emerson learns what has happened from the inquisitive butler Anthony Smith and goes after his sister. He manages to save Myrna at the Petit Maxim, but falls victim to the Blue Hand himself. Mr. Snobbits, the club’s leaseholder, who has several previous convictions, claims to know nothing. After being questioned at Scotland Yard, he meets Nurse Harris from Mangrove’s asylum, whom he evidently knows. The nurse tells Inspector Craig and Sir John that her murdered colleague, Agnes Dairen, had written a report disputing Mangrove’s assessment and concluding that Dave was not insane. The report and other notes critical of Dr. Mangrove have been missing since Nurse Dairen’s death. Fearing that Scotland Yard will search the asylum, Mangrove has numerous cells emptied and patients hidden in the basement. It turns out that the asylum doctor is beholden to a mysterious “Boss,” who has ordered him to eliminate Myrna the following night. That evening, guard Reynolds and a patient leave the clinic in a delivery van with the sinister murder weapon. They drive to Gentry Castle, where the Blue Hand murders another member of the Emerson family: Charles. To double-cross his Boss, Mangrove abducts Myrna and takes her to his asylum. He does not hesitate to use sedatives, snakes, and rats to make Myrna sign a declaration of renunciation. But the young woman refuses to give in. Mangrove tells the “Boss” that he does not know where Myrna Emerson is. Nurse Harris finds the files belonging to her murdered colleague, but Mangrove catches her with them. The unscrupulous doctor’s subsequent torture drives the nurse insane. Inspector Craig and Sir John arrange for the asylum to be searched. However, the police officers do not discover the hiding place where the patients and Myrna are concealed. Dave reveals his true identity to his stepmother and once again insists that he is innocent. That night, he escapes an attack by the Blue Hand. Craig manages to free Myrna from the asylum and arrest Dr. Mangrove. While questioning Mangrove, the investigators learn that the Earl of Emerson was innocent and had taken the blame for the crimes committed by his second wife, Lady Emerson. In America, the Earl, who has since died, became very wealthy. In his will, he named his five children as heirs. The inheritance would pass to Lady Emerson only after the children had died. Inspector Craig and Sir John confront Lady Emerson and the lawyer Lionel Douglas, who is also at Gentry Castle, with the results of the investigation. Douglas admits that he knew about the will and the Earl of Emerson’s death. He also confesses that he is Lady Emerson’s lover. Nevertheless, Douglas and Lady Emerson both claim to have had nothing to do with the Blue Hand murders. Craig and Dave investigate a secret passage used by the Blue Hand to carry out its attacks. Several secret doors and a gloomy maze lead, of all places, to the gardener’s cottage, where Dave is supposed to have murdered the gardener Edward Amery. Dave and the inspector unmask the Blue Hand as Amery, the supposedly dead gardener. Craig arrests Mangrove’s accomplice, Reynolds. Inspector Craig now knows who is really behind the crimes. After the Earl of Emerson’s death, Lionel Douglas arranged for Dave’s arrest and subsequent escape so that Dave would be blamed for the murders organized by Dr. Mangrove. But the real “Boss” is revealed to be Richard Emerson, who has by now been overpowered and tied up by the butler Anthony.