The film has been found to confuse many viewers. Below is a detailed synopsis of the film's events.At a desert island retreat owned by wealthy industrialist George Stark (Teodor Corra), a group of people have assembled for a weekend getaway of relaxation. Foremost among the guests is Professor Gerry Farrell (William Berger), an inventor/scientist who is badly in need of a vacation. While the first night passes uneventfully, with the group sitting around the fireplace at Stark's large seaside house singing folk songs, Farrell is enraged to discover on the next morning that Stark, together with several of the guests, has planned this entire getaway as an opportunity to coerce him in to selling his latest invention: a formula for industrial resin.Farrell is immediately established as a decent man, and although his marriage to his wife, Trudy (Ira Furstenberg), appears to be content, she is actually involved in a secret lesbian affair with Stark's artist wife Jill (Edith Meloni). Actually, none of the relationships are particularly healthy. Stark's business partner, Nick (Maurice Poli), is verbally abusive to his coquettish wife Marie (Edwige Fenech), but does not object to her sleeping with other men, one of whom is the houseboy and manservant Charles (Mauro Bosco). Stark is less of a husband to Jill than he is a business manager. Stark arranges for Jill to have her paintings and artwork publicly displayed and is also a source of constant criticism. The sole happy couple appears to be Nick's co-worker Jack (Renato Rossini), and his wife Peggy (Helene Ronee). Also among the guests is Isabelle (Justine Gall), a young teenage girl who seems to be in Stark's care while her parents are away.As Stark, Nick, and Jack badger Farrell for the secret of the formula by offering him $1 million each from their Swiss bank accounts, Jill makes a horrible discovery on the beach: the dead body of Charles. Having already sent the motor launch away to prevent Farrell from leaving, and with the radio strangely out of commission, Stark has no way of contacting the mainland. So, Charles body is moved into a large walk-in freezer where it hangs with other 'chunks of meat'.A little later, Farrell himself is the next victim. While he is walking alone on the beach, a sniper shoots him down. Trudy and Jill, walking hand-in-hand nearby, hear the gunshot and find Farrell's dead body and run way to tell the others. But the sniper is revealed to be Isabelle, who places Farrell's body in a rowboat and pushes him out to sea.As tempers flare to Farrell's killing and 'disappearance', the killings then escalate with alarming regularity. Peggy, standing on the balcony of her room, gets shot to death by an unseen assailant. Jack arrives on the scene first, and accuses Stark of being responsible, which he denies. Soon after, Marie turns up dead, having been tied to a tree with a knife sticking out of her chest. Then, Jill turns up dead in her bathtub after being electrocuted. Each of the bodies are placed in the freezer. Rather than risk anymore bloodshed, the four remaining survivors of Stark, Jack, Nick, and Trudy hold up in Stark's living room for the night. In this way they believe, the killer cannot strike without revealing him or herself. After bickering with Trudy, Nick storms off into the night. The next morning, he too is found dead, and his body is placed in 'cold storage'.Up to this point, Stark is the most possible suspect when he sneaks out of the house and uncovers a motorboat which will take him to the mainland. As he returns to the house to get supplies, Jack confronts him where he reveals himself to be the killer, having killed off everyone to steal the $1 million cashiers checks from their bank accounts. Before Stark can to anything, Jack shoots him dead. But its revealed that Jack has not been acting alone. After killing Stark, Jack meets in the freezer with Trudy who is the real mastermind behind the whole scheme. Trudy had met with Jack before arriving on the island and offered to kill everybody so she can steal the million dollar cashier checks from Stark, Nick, in order to hand him over the formula for the resin. Jack even was forced to kill Peggy too because she got too close to discovering his plan. Jack then offers to hand Trudy over the three $1 million cashier checks, as she produces the microfilm for the resin formula. But Trudy tries to pull the same trick on Jack, by shooting him in the head, and stealing the three million dollar checks for herself. But having anticipated Trudy's betrayal, Jack manages to shoot her with his gun before expiring. At this point, Isabelle, who had been hiding in the secret passageways in the house through most of the movie, enters the freezer where Trudy and Jack killed each other, and calmly collects the three checks from Trudy's handbag.Epilogue. In an incredulous, off-the-wall twist set months later, as well-dressed Isabelle arrives at the state prison where Farrell is incarcerated. It turns out that Farrell, the apparent 'hero' of the story, actually stole the invention of the resin himself, murdering the true inventor in the process. Together with his wife, Trudy, it was Farrell who concocted the whole scheme of murder and duplicity for the sole purpose to steal Stark's, Nick's, and Jack's money. But Farrell's treachery has not gone unpunished. In their conversion on the island earlier, Farrell had met with Isabelle and had her shoot him with a drugged bullet to make it appear that he would be dead to get away from the others, whom he duped Isabelle into thinking were trying to kill him. But after shooting and drugging the professor, Isabelle pushed him out to sea in an open boat hoping someone would rescue him. Unfortunately for Farrell, his rescuers ended up being the police on their way to Stark's island and, unknown to him, the drug Isabelle used on him made him so delirious which made him confess his crimes of murdering the inventor for the resin and orchestrating with Trudy, who subcontracted Jack, to murder everyone on the island for the money. Isabelle runs off with the $3 million, leaving Farrell behind on death row to be hung for his crimes.