 The scene is India in the middle of the 19th century. Deep in the impenetrable forests of the Dark Jungle, the palace of the Maharajah of Rangnagar is raided by robbers who want to steal his legendary treasure. A battle takes place in which almost all the family and all the servants and soldiers lose their lives. There are only three survivors: Prince Tremal Naik, the Maharajah s little son, Gita, his nurse, and the bold warrior Kammamuri. Kammamuri takes it upon himself to look after the child. He takes him to live in a fisherman s hut by the river and brings him up to become a peace-loving young man who makes the mysterious world of the jungle his home. For a long time Tremal Naik, unaware of the terrible fate his family has suffered, believes Kammamuri to be his father. At the same time, in Aurangpore, Ada, the little fair-haired daughter of the British Colonel Corishant, is kidnapped, disappearing without trace. Her despairing father does not suspect that Mohan Singh, the Maharajah of Aurangpore, is at the same time the secret leader of the Thugs, a fanatical sect, and, believing little Ada to be in possession of mystical powers, is planning to bring her up to become the priestess of the sinister goddess Kali. The girl is taken to a remote valley, where Mohan Singh uses magic powers to put her into a trance and by means of black magic prepares her for her future task of serving the evil goddess. The loss of his daughter Ada almost drives Colonel Corishant mad. He instigates numerous searches but none of them is successful. Ada is nowhere to be found. Colonel Corishant has no one left to comfort him but his wife Sarah and his elder daughter Deborah. Meanwhile, in the jungle, Tremal Naik has learnt from Sonali, a girl he loves like a sister, that Kammamuri is not his real father. However, when he asks about his parents he is merely told that they are dead. Kammamuri conceals his true origins. Years pass by. Ada is still in the hands of Mohan Singh, who in his role of Maharajah, pretends to feel profound pity for the sorrowing parents. One day, when hunting, Tremal Naik comes across a secret underwater passage to the hidden valley in which the Thugs live. In this completely solitary paradise he secretly watches a blonde girl: Ada. Fascinated by Ada s grace and beauty, Tremal Naik decides he must see her again. Shortly after this, he visits his friend Father Flores, the head of a mission station in the jungle. Here he meets Sarah, Ada s mother. He is immediately struck by the likeness between Sarah and the girl in the jungle. He mentions this to Sarah and hears the story of how Ada was kidnapped ten years earlier. He returns to the valley of the Thugs and succeeds in helping Ada, who is under Mohan Singh s spell, to escape. Meanwhile Corishant, having heard Tremal Naik s story from his wife, and believing that Kammamuri and Tremal Naik are Ada s kidnappers, has Kammamuri s fisherman s hut burnt down and the old man taken prisoner. On their flight from the ruthless Thugs Tremal Naik and Ada battle their way through the pathless jungle. Ada is still under the evil influence of Mohan Singh, but the more she learns to trust Tremal Naik and feels herself protected by his love, the weaker this influence becomes. Tremal Naik s patience and sensitivity gradually help Ada to regain her memory of her origins. Ada is astonished to observe the assurance with which Tremal Naik finds his way in the jungle, his closeness to nature and his knowledge of plants and animals. In the unreal beauty of their surroundings the two young people soon grow to feel love and tenderness for each other. The lovers do not know that Kammamuri has been sentenced to death by Ada s father and that he will only be set free at the very last minute, when Sarah realizes that Kammamuri once saved her daughter s life many years before. Tremal Naik is horrified when he comes upon Kammamuri s burnt-out hut; he makes his way with Ada to Gita, his old nurse. Their arrival is observed by one of the Colonel s soldiers, and soon afterwards the Colonel and his men appear at Gita s hut. Beside himself with joy, the Colonel embraces the daughter he had believed dead. Thinking Tremal Naik to be Ada s kidnapper, he has him arrested. But Tremal Naik, with the cunning of a jungle animal, manages to escape. Mohan Singh, beside himself with rage at Ada s disappearance, also learns that she was with Tremal Naik when she was found. He assumes - rightly - that Tremal Naik has rescued Ada, and gives his Thugs orders to kill him. Tremal Naik flees to Father Flores  mission station, where he finds Kammamuri again. But the Thugs are on Tremal Naik s track and that night, in order to kill Tremal Naik and Kammamuri, they attack the mission station. A fierce battle ensues, in which Tremal Naik fights bravely. Although he succeeds in driving away his assailants, he still cannot prevent Kammamuri from being seriously wounded. Without considering the fact that he himself, a wanted man, is in great danger, Tremal Naik takes his foster-father to the Colonel s camp and asks for help. Stefan Kruger, the army medical officer, for whom Tremal Naik s childhood friend Sonali is now working as a nurse, operates on Kammamuri and saves the old man s life. Tremal Naik has been arrested and is awaiting trial. Ada has meanwhile managed to convince her sister Deborah of Tremal Naik s innocence, and Deborah asks Richard, her fiancé, to conduct Tremal Naik s defense. Richard discusses the case with Judge Forbes, and the latter asks Mohan Singh s advice. To the judge s astonishment, Mohan Singh advises him to sentence Tremal Naik to death saying that little Ada s kidnapping was, after all, a capital offence. No one suspects that it is in Mohan Singh s very own interest to get Tremal Naik out of the way. Although there is no conclusive evidence for Tremal Naik s guilt and although - in a brilliant summing-up speech - Richard proves his innocence, Tremal Naik is sentenced to ten years  hard labour on the prison island of Davenpur. No one has ever returned alive from this dreaded island. Ada is in despair. She is not even given the opportunity to take leave of her lover. When Kammamuri hears of Tremal Naik s sentence he knows what he must do. He, who after the murder of Tremal Naik s family swore never to pick up a weapon again, must now try to save the innocent young man from his fate. He arms himself and makes his way through the jungle in the direction of the prison island of Davenpur. Soon he catches sight of the group of mercenaries who are to take Tremal Naik to the island. They, however, have no intention of carrying out their task; instead they tie Tremal Naik to a tree and are about to leave him to the poisonous snakes of the jungle - and to certain death. But Kammamuri arrives on the scene at the very last minute, and before the eyes of the astonished Tremal Naik, who only knew Kammamuri as a gentle, kind man, he overpowers the mercenaries in a truly masterly and courageous fight. Just as Tremal Naik is on the point of thanking his saviour, however, the latter disappears without a trace into the darkness of the jungle. The next day in Aurangpore rumours of Tremal Naik s death are circulating. Ada is beside herself with grief. And suddenly she again feels the deadly influence of Mohan Singh, who has still not given up hope of regaining his power over Ada. In order to achieve this, he arranges a banquet to which he invites the Colonel s family. At the same time he sends out four of his Thugs to ascertain whether Tremal Naik is really dead. Tremal Naik has meanwhile appeared at the house of Stefan Kruger, the medical officer, who, together with Tremal Naik s childhood friend Sonali, is overjoyed to welcome him. But the Thugs have seen him arrive and suddenly attack from an ambush. Sonali tries to protect her friend by throwing herself in front of him, and is killed by a poisoned dagger. Tremal Naik succeeds in overpowering Sonali s murderer. Stefan Kruger calls Colonel Corishant and his men to their aid. Finally the murderer admits to having been ordered to kill Tremal Naik by Mohan Singh. Now at last Colonel Corishant realizes that Tremal Naik is innocent. But suddenly, to his horror, he remembers that Ada, her sister Deborah and their mother are at this very moment in Mohan Singh s palace. And indeed - Mohan Singh has meanwhile been doing his utmost to regain his power over Ada. While Colonel Corishant, his soldiers and Tremal Naik are trying to storm the palace, Mohan Singh puts the girl into a trance. He forces her to invoke the goddess Kali and to conjure up destruction, blood and death. During the fierce battle that follows Mohan Singh succeeds in escaping with Ada through a secret door. Deborah, seeing this happen and wanting to go after her sister, is also carried off by the Thugs. But Tremal Naik knows where the Thugs have their secret temple and rightly assumes that is where they have fled to. In the Thug s temple preparations are being made for a Black Mass, in the course of which the goddess Kali is to take possession of Ada s body. To make this possible Ada is to sacrifice her sister Deborah to the evil goddess. Just as Ada - in a deep trance - is obeying Mohan Singh s command and raising a scimitar to kill her sister, Tremal Naik, the Colonel and his soldiers break into the palace. Ada sees Tremal Naik and the spell is broken. Aroused from her trance, she flings herself into her lover s arms. A last, deadly struggle begins. Many of the Thugs are killed, wounded or taken prisoner. Only Mohan Singh, their leader, is finally able to make his escape. Deborah falls into the arms of Richard, her fiancé. Ada returns to the jungle with Tremal Naik, to the ruins of his parents  palace where, suddenly, Kammamuri appears and tells Tremal Naik the truth about who he really is. The young prince is moved and, at the same time, happy. Together with Ada he rediscovers the scenes of his childhood.