Khanna, a wealthy man, hires an assassin to murder his rival, Sohanlal. Khanna then informs the victim's niece, Asha, of his death, on the phone. As Asha screams, an intruder enters and shoots Khanna dead.
A few days later, Asha wins a trip to a foreign country with six others: Barrister Rakesh, Dharamdas, Kishan, Dr Acharya, Madhusudan Sharma, and Kitty Kelly. The aircraft carrying the six winners and crew member Anand is forced to make an emergency landing at an unknown island. However, as soon as Anand and all the passengers alight from the plane, it takes off, leaving everyone stranded.
A mysterious, unseen woman starts singing a song. The song is heard at different points in time during the film without the woman being seen. Then the group notices a mansion and enters it. The mansion seems to be unoccupied except for a butler. Dharamdas finds a diary that reveals that they are all connected to a crime, and that they will all be killed.
Anand discovers Dr Acharya has brought with him a bottle of poison, and Dharamdas has brought a dagger. The butler's actions indicate the presence of an unknown person in the house.
Anand starts flirting with Asha while Rakesh and Kitty become close. Everyone is suspicious of everyone else.
Anand and Asha find Kishan's corpse. The killer has left a note stating that Kishan had murdered Sohanlal. The group deduces Dharamdas killed Kishan but he pleads innocence. Dharamdas is later found dead. Anand concludes the culprit is among them.
It becomes clear that everyone in the house was connected to Sohanlal. Kitty was Sohanlal's secretary. Rakesh wrote Sohanlal's will on Khanna's orders. Kitty sent the will to Rakesh on Khanna's instructions, though neither knew about the other.
Anand notices Rakesh hiding an axe. Later, Dr. Acharya arrives, screaming that Sharma has been killed with an axe. The killer leaves another note stating Sharma was Khanna's co-conspirator in Sohanlal's murder.
Anand accuses Rakesh of Sharma's murder. Dr. Acharya catches the butler acting suspiciously. He learns the butler's secret and a scuffle ensues between them. The doctor enters the dining room, utters Anand's name, and collapses in the presence of Asha and Kitty. They realise that he has been stabbed. Asha starts questioning her faith in Anand.
Plot Summary from Wikipedia - See more on en.wikipedia.org Text under CC-BY-SA license