Plot

A teenager encounters romance, intrigue and a search for stolen jewels during her visit to the island of Crete.

British musicologist Frances Ferris (Joan Greenwood) and her late teen niece Nikky Ferris (Hayley Mills) are travelling through Crete recording Greek folk songs for the BBC. In the usually quiet coastal town of Aghios Georgios, they manage to get a room at an inn called "The Moon-Spinners", despite the people at the inn being busy preparing for a wedding, and no one there, except Alexis (Michael Davis), the young teen son of the proprietress Sophia (Irene Papas), he who is fond of spouting current popular Americanisms in his slightly broken English, seeming to want them there. Frances and Nikky learn from Alexis that the unwelcoming feeling is all because of his maternal Uncle Stratos (Eli Wallach), who has become a man suspicious of anyone ever since his recent return from London after being away for fifteen years. Beyond those there for the wedding, the only other guest at the inn is a young Englishman named Mark Camford (Peter McEnery), who they befriend. Nikky is too preoccupied with her own suspicions and mistrust of Stratos truly to see that there is something more sinister in the feelings between Stratos and Mark. Although they don't say anything to each other directly on the matter, Stratos knows why Mark is in Aghios Georgios and is always skin diving in the nearby Bay of Dolphins, and Mark knows that Stratos, and by association his other nephew Lambis (Paul Stassino), will be after him if he gets too close to what they have hidden in the bay before their intended method of disposal. By getting close to Mark, Nikky may unwittingly get caught up in what is the very dangerous and potentially life threatening game of cat-and-mouse between Stratos and Mark.—Huggo

Start with a fortune in stolen jewels. Add a dash of danger. A pinch of romance. Season with Hitchcock-like intrigue and comic flair. What do you have? A mystery thriller for the whole family. Set against the sun-bleached beauty of the Isle of Crete, the story pits a young English tourist (Hayley Mills) against a wily Greek jewel thief (Eli Wallach). Mistaken identities and perilous escapes -- including a nail-biting battle with a windmill -- lead the junior-miss detective to a final confrontation aboard the yacht of an eccentric millionairess (Pola Negri) with a passion for priceless gems and pet cheetahs.—Anonymous

Young English girl Nikky Ferris (Hayley Mills) and her Aunt Frances (Joan Greenwood) arrive at "The Moon-Spinners", a hotel on Crete, to a less than enthusiastic welcome. The coolness of the owner is only out-done by the surliness of her brother Stratos (Eli Wallach), recently back from London. But then there is nice English lad Mark Camford (Peter McEnery) with whom to make friends, at least until Stratos and his pal take a shot at him one night. When Nikky helps him hide, she finds the Greeks are after her too.—Jeremy Perkins {J-26}

Nicky Ferris and her aunt Frances are traveling on a bus to Crete. When they arrive at their hotel, the Moon Spinners, a village wedding is in progress. The proprietress, Sophia, did not receive the telegram Nicky sent to reserve a room. She says there are no rooms available. Nicky and Frances are exhausted and after Sophia's teenage son Alexis intervenes, she reluctantly gives them a room for the night. But her brother Stratos is furious. Since his return from England he has been acting strangely. He does not want guests staying at the hotel but promises Sophia that soon they will have all the money they want. Sophia is very suspicious of his dealings with what she calls a strange Englishman.

Nicky notices a young man in the crowd and learns he is also a guest. His name is Mark Camford and he is on holiday from England. He notices Stratos leaving and asks if he is going snorkeling in the Bay of Dolphins. This makes Stratos angry. Mark tells Nicky that he also likes to snorkel in the bay. They dance and enjoy the wedding festivities. Before saying goodnight, Mark asks Nicky to meet him the following day for a picnic.

Instead of going to bed, Mark returns to the Bay of Dolphins to spy on Stratos, who is in a boat. He does not notice that he has been followed. A fight ensues and Mark is shot. He dives into the water and disappears. Stratos and the other man assume he has drowned. Later, Stratos goes to Mark's hotel room and takes all his belongings.

The next morning, Nicky is puzzled when Mark doesn't show up for their picnic. Stratos tells her he checked out very early that morning. Not believing him, Nicky goes on a search. She finds Mark's shoe on the beach and traces him to a nearby church. He was shot in the arm but refuses to explain what is going on. Seeing that he needs medical treatment, Nicky covers him with her sweater and races back to the hotel, stopping first in Mark's room to bring him fresh clothing. But there is nothing there. She takes her aunt's traveling blanket and first aid kit, plus a bottle of brandy from the bar. Frances is listening to a group of native women singing and doesn't notice Nicky sneaking in and out.

Once Mark is attended to, he orders Nicky to leave but he still won't explain why Stratos is after him. Back at the hotel, Frances reports the loss of her blanket and first aid kit. Stratos realizes that Nicky must have taken them for Mark, which means the young man is not dead after all. He encounters Nicky in the village and she tries to steer him away from the church. But he goes there, forcibly taking her with him, and finds her blood-stained sweater.

As the day passes, Frances becomes worried when Nicky doesn't return. Stratos assures her that Nicky has probably gotten lost and will soon turn up. Alexis is riding his donkey near a windmill when he hears a cry for help. Stratos has tied Nicky to a post in the loft. Just then Mark turns up and they rescue her. But Stratos is not far behind and the pair set off for the next village to summon the police. On the way Mark tells Nicky his story. In London he worked at a bank but was fired after a client's jewels disappeared. He suspected Stratos, who fled the country soon after. Determined to clear his name, Mark followed him to Crete and the Bay of Dolphins. He is positive that the missing jewels are somewhere underwater.

Sophia suspects that her brother is involved in Nicky's disappearance. Once again he threatens her and hints that something might happen to Alexis if she doesn't keep her mouth shut. Frances is frantic and Stratos makes a point of organizing a search party for Nicky.

Stratos's friend catches up with Nicky and Mark. He is overpowered and knocked out, and now the pair have his shotgun. They decide to spend the night in some ruins. Stratos shows up but is spooked by the feral cats occupying the ruins. After a cursory search, he leaves.

The next morning, Nicky and Mark are awakened by an elderly man who turns out to be John Gamble, the British counsel. His explanation for being there, to observe the ruins at daybreak, sounds rather fishy. But Mark's injury needs medical treatment, so they agree to accompany him to his home. His wife Cynthia is a nurse and will be able to help Mark. Gamble persuades them to leave the shotgun behind. By the time they reach the consulate, Nicky has told Gamble all about Stratos. Gamble assures them they will be safe there. He will send a car for Frances and arrange for them to be flown to a hospital in Athens.

Cynthia takes them upstairs. Gamble goes into a room where Stratos is waiting. He is very angry at Stratos for bungling the operation and asks how he thought two British subjects could disappear without anyone noticing. Stratos mumbles a weak excuse but Gamble is through with him. He orders Stratos to return to the village and wait for further instructions.

After a bath and some food, Nicky is feeling much better. Cynthia brings her a dress to wear until her aunt arrives with their luggage. But she fears Mark's injury will become infected. She gave him some medicine and he is sleeping. Nicky goes downstairs and by using Gamble's telescope, observes a yacht on the water. Gamble turns her attention to something else, obviously trying to distract her. When Nicky finally sees Mark, he is very suspicious of the Gambles. He tells Nicky that the jewels cannot be sold on the open market, so Stratos will try to find a private buyer. Madam Habib is a wealthy eccentric who travels on a luxurious yacht. She collects jewels and Stratos will likely approach her. Nicky thinks the yacht she saw might belong to Madam Habib, which turns out to be true.

Mark believes that Cynthia has deliberately drugged him. He tries to get dressed but collapses. Frances arrives and Gamble sends them to the airport in a hearse, the only vehicle available because a street festival is going on. Frances is up front with the driver while Nicky and Mark are in the back. He is wearing street clothes under his pajamas and tells Nicky he is returning to the Bay of Dolphins. She follows him but can't keep up. He boards a bus and is gone.

Nicky steals a boat and goes out to the yacht. She is taken on board and tells her story to Madam Habib, who is very suspicious of her. Meanwhile, Stratos and his accomplice retrieve the jewels from an underwater container in the Bay of Dolphins. They escape in their boat just as the police, accompanied by Mark, arrive.

Madam Habib admits that she is expecting Stratos and forces Nicky to hide in a closet. Stratos arrives with the jewels, giving Madam Habib only a brief glance at them before demanding immediate payment. When she leaves to get the money, Nicky sneezes inside the closet. Stratos finds her and they struggle. Just then the police burst in and arrest Stratos. The jewels will be returned to their rightful owner and Mark's name is cleared.