On a dark night, a wealthy man, Seth Sohanlal, is fatally struck by a speeding car outside a hotel and dies on the spot. In a room overlooking the hotel, Khanna [Hiralal], Seth Sohanlal's murderer, arranging the crime with cold efficiency, hands a bundle of banknotes to the unseen driver who arrives shortly after. Khanna then makes a string of calls to unseen associates: to a doctor to assemble a medical certificate, to a mysterious young girl to ensure the will reaches the proper recipient, and to a lawyer who will handle the will when it arrives the next morning. Soon after, Khanna informs Seth Sohanlal's niece, Asha [Nanda], of her uncle's death. As Asha screams in anguish, gunshots crack from the other end of the line—the intruder in a long coat and hat has entered Khanna’s room and shoots him dead. The opening sequence plants a mood of cold conspiracy, where every call seems to tighten the net around the living.
A few days later, the atmosphere shifts to a glitzy, dangerous glamour at a nightclub, where a “lucky draw” promises a free fortnight-long trip abroad. The seven winners—five men and two women—are introduced as if plucked from the shadows of Seth Sohanlal’s finances: Barrister Rakesh [Pran Sikand], Dharamdas [Dhumal], Kishan [Manmohan], Kitty Kelly [Helen], Dr. Acharya [Madan Puri], Madhusudan Sharma [Tarun Bose], and finally Asha, who now appears steadier, though the past weighs heavy on her. The group is thrilled and uneasy in equal measure as the announcer’s glittering voice sells an escape that may soon become a trap.
The plane’s departure begins with a routine, almost too easy, but is derailed by a sudden emergency landing on a remote island due to technical problems. As the passengers disembark, the pilot shockingly dumps their baggage and takes off, leaving them stranded. A haunting, unseen girl begins to sing, her voice floating through the air yet never visible to the castaways. They follow the singing to a sprawling mansion, an imposing structure that seems deserted except for a comical, lungi-clad butler, Mehmood, who greets them by name and reveals that he has been expecting their arrival. He keeps a diary that records daily expenses and, more chillingly, contains a message addressed to the entire group accusing them of having conspired to kill Seth Sohanlal. That night, Anand [Manoj Kumar], the sole crew member on board who appears to have managed to bring a gun, discovers that Dr. Acharya has a bottle of poison and that Dharamdas carries a lethal dagger. Romantic tensions flare as Rakesh and Kitty grow closer, while Anand flirts with Asha. Yet the butler’s calm and meticulous demeanor hints at a deeper knowledge of everyone’s secrets.
The mood darkens quickly when Kishan is found stabbed to death, a half-smoked cigar resting near his body and a letter accusing him of being the vehicle of Seth Sohanlal’s death. The group initially suspects Dharamdas, but he pleads innocence and is soon strangled to death. As accusations fly, Rakesh accuses Dr. Acharya of having poisoned Dharamdas, and the web of connections to Seth Sohanlal’s murder grows more tangled. Kitty is revealed to have been Seth Sohanlal’s private secretary who sent his will to Rakesh on Khanna’s orders, while Rakesh himself wrote the will on Khanna’s instructions—though neither of them was aware of the other’s role. The tension intensifies as Anand observes Rakesh concealing an axe, and Dr. Acharya appears with the news that Sharma has been murdered with an axe. The body count climbs, and the group—Anand, Rakesh, Dr. Acharya, Asha, and Kitty—find themselves reduced to five, the mansion shrinking around them like a trap.
That night, the butler’s suspicious actions come into sharp focus when he confronts Sharma’s killer. In the ensuing confrontation, Dr. Acharya arrives and collapses, whispering Anand’s name before dying. The tension explodes into fear as Kitty goes for a walk on her own and is found strangled to death, her body discovered with Anand’s hat nearby. Rakesh pursues a fleeing Anand but loses the trail. In a brutal twist, Rakesh attempts to assault Asha in the mansion’s dark corridors and is found dead with two daggers buried in his back. The lights suddenly fail, and fear accelerates into a near-hallucinatory sense that the killer has arrived to finish the job.
Asha lurches toward safety, only to be seized and dragged into a secret room. There, the killer reveals himself as Sharma, alive and orchestrating everything with the help of the butler, who had merely been acting as a caretaker to mask a more sinister plan. Sharma explains that he had used the butler to set the stage for the murders, killing Kishan and Dharamdas and convincing Dr. Acharya to pretend to be dead so he could secretly pursue the truth and capture the others. Sharma’s ruse seems nearly complete until Anand bursts onto the scene, revealing that he is not just a flight attendant but an undercover police inspector on a mission to capture Sharma, whose real name is Madanlal. Madanlal confesses to a series of crimes tied to a larger smuggling operation shared with Khanna and Seth Sohanlal, including the brutal abuse of Madanlal’s sister and the deaths that followed. Khanna and Seth Sohanlal had betrayed him in prison, and Madanlal had escaped to exact his revenge by turning the “lucky draw” into a trap that would reveal and ruin his former accomplices.
A tense confrontation ensues as Madanlal ties up Anand and Asha and forces them into a game of Russian Roulette. The butler, secretly a crucial ally to Anand, arrives in time to untie him, and Anand unleashes a counterattack that disables Madanlal just as reinforcements arrive. An airplane full of police lands on the island to take Madanlal away, bringing the island’s nightmare to a close. The final twist reveals that the singing voice the group heard all along belonged to the butler’s sister, Naina [Naina], who has been mentally ill and hidden from view. With the danger finally behind them, Anand, Asha, the steadfast butler, and Naina depart the island on the waiting airplane, leaving the cursed mansion behind.
In the end, the narrative threads converge into a single, unsettling truth: the intertwining of greed, betrayal, and long-buried pasts can turn a glossy vacation into a deadly trap. The island’s mystery is resolved not only through police intervention but through the perilous choices each survivor made under pressure. The story closes with the survivors boarding the aircraft, a fragile sense of relief tempered by the knowledge that scheming and vengeance can masquerade as ordinary fate—and that some voices, even when unseen, can still echo with danger long after the lights go out.
