Der rote Faden (1915)

Hans Wenden, who works at a chemical factory, has committed embezzlement and is sentenced to two years in prison. Behind bars, Wenden meets fellow inmate Martin Knorr, and the two become close confidants. They are released on exactly the same day. When Wenden gets home, he learns that his father’s death has made him a rich man, and tries to get rid of his prison acquaintance by giving him a large sum of money. Knorr soon spends it all and hopes Wenden will help him again, but Wenden has suddenly disappeared. With the help of an accomplice, Knorr discovers that Wenden has assumed the false name Dr. Burns and, under that name, visits the home of Dr. Karl Hopes, who is associated with the very chemical factory where Wenden once had sticky fingers. Dr. Hopes’s niece, Thea Holm, also lives in the house. One evening, the doorbell rings, and Thea opens the door to see who is there. But no one is in sight, so she goes back inside. There she finds her uncle Karl—dead. The plans for a gold mine, which had held Uncle Karl’s interest until the very end, are missing. Master detective Barker Swift takes the case, commissioned by Thea to solve it. His investigation suggests that the thief—and thus probably the uncle’s killer as well—must have secretly lowered himself into the house through the chimney. Hopes must have seen him and suffered a heart attack from the shock. Thea introduces the supposed Dr. Burns to Swift as a family friend, but the detective instinctively suspects that the man is not who he claims to be. His footprints in the sand outside the front door look suspiciously like those Swift found in the soot in the chimney. Meanwhile, Burns, alias Wenden, finds a note at home in which Knorr asks him to meet at the tavern “The Gray Donkey.” There, they hatch a criminal plan: Thea is to be kidnapped, and the detective lured to the home of Burns/Wenden, whom he has been watching with suspicion. But the Wenden house is merely a trap for Barker Swift. Instead of finding the stolen gold-mine plans or the kidnapped Thea, he is attacked there. Barker’s chauffeur rushes to his aid, and together they overpower the villain. When Burns appears, he tries to get rid of the detective with a technical trick: a staircase can split into two parts, causing Swift to slide down into a water tank. But Swift had anticipated something of the sort and does not fall for the trick. Disguised as a beggar—the same one who had earlier tried unsuccessfully to eliminate Barker on Wenden’s orders—Swift enters Wenden’s room and takes the gold-mine plans from him. Meanwhile, Barker’s chauffeur has alerted the police and takes Burns, alias Wenden, into custody. The captive Thea is freed.