Nine Guests for a Crime

The movie opens with a beach scene, with a young couple having sex on the sand surrounded by four men with shotguns driving up. The young man on the beach is chased and shot by the small mob, before being buried alive in the sand.

In present time, a blended family of nine makes their way to a Mediterranean island villa for a vacation, arriving by sailboat. Ubaldo is the family patriarch and the owner of the villa resented by his sons' wives. Ubaldo's young wife Giulia married him for his wealth, but also cares for him in his old age. Lorenzo has a loveless relationship with his wife Greta. Michele's wife Carla is recovering from a traumatic gang rape, has a suicidal ideation history, and brought a revolver, which shocks her husband. Patrizia is a psychic, who predicts death on the island, but her husband Valther merely degrades her whenever she drinks. Elisabetta, Ubaldo's sister, brought rifles along with her for hunting. Affairs begin to happen on the island: Valther with Greta, and Michele and Giulia. Lorenzo doesn't strain to stop Greta, and Carla wakes up to discover her husband and Giulia during sex.

In the meantime, a killer is trying to take out the family members one by one. When swimming to the docked boat in a wetsuit and scuba gear, the killer murders the two sailors, stabbing one with a diver's knife and shooting the other with a silenced pistol. The killer then falls back off the boat and swims away. The next day, Carla joins Michele and Elisabetta while they swim in the ocean waters, but she's later seen drowning and sinks underwater. Michele dives in after her while the other men try to see where she is from the rocky cliffside, but there's no sign of Carla. They find the sailboat is missing, and the spare motorboat's been tampered with, trapping everyone on the island. Patrizia is most distressed from seeing the very dangers she predicted.

Michele suspects Giulia of killing Carla, which Giulia takes great offense from. Elisabetta screams and draws the whole household to her. She rambles she dreamed of a man named Charlie, who she was murdered by. The men tell Giulia Charlie is a man who disappeared twenty years ago. The power is cut out, and the killer smothers Ubaldo in his bed with a pillow. When Giulia goes downstairs to get sedatives for Elisabetta, she is horrified to see Ubaldo dead, and Valther confirms he hears no heartbeat. Lorenzo accuses Giulia of poisoning Ubaldo with his medicine for the inheritance, but Giulia mentions every son and son-in-law in the family inherits. Lorenzo simply affirms they're all in danger. They all make it to the morning, but Patrizia gloats she was right while she's drunk, despite attributing the murders to a restless "ghost" of a murder victim on the island.

The men see Elisabetta walking out to the rocky edge, so they follow her. She's looking for a woman's bloody corpse she saw in her dream. When Patrizia is seen above them on the cliff edge, then everyone turns away from her, she plummets off to her death on the rocky shore below, left a bloody corpse just like Elisabetta said. Valther is distraught and furious, proclaiming the killer is murdering the heirs. Elisabetta points up at the cliff to a presumed decayed, bloody figure, which she says is Charlie taking his revenge. When Giulia returns to the house and sedates Elisabetta, Greta tells her about what Michele confessed: Charlie was Elisabetta's lover, but because he was poor and the family found themselves untouchable, Ubaldo and his sons hunted Charlie down and killed him. Greta is convinced the murders are indeed related to Charlie's murder.

The men agree to exhume Charlie's body, but he's not in the grave. Elisabetta watches them from a rock, so they agree they'll have to find Charlie or make Elisabetta talk. The men grab their guns, and the survivors search the house. Greta opens a door to find Charlie's corpse behind it, heavily rotted, confirming he's not the killer. While Valther throws Charlie's remains into the ocean, he sees a figure disguised as Charlie and tries to run after them. He falls into a trap in the sand, before the killer throws a net over Valther, shoots him three times, pours gasoline on him, and fires a final shot to combust the gasoline and incinerate Valther.

Lorenzo is horrified to hear Giulia left Greta alone and goes to find her. Assuming she's asleep, Lorenzo tries to wake Greta, but she revealed to be beheaded when her head rolls off the bed to the floor. Giulia runs into the bathroom when she becomes nauseous, but the killer creeps out of the shower before strangling her to death. Lorenzo and Michele hear screams and run to the living room. They find Elisabetta, who directs them to see Charlie outside, running from the house. Michele sees smoke from downstairs, then a figure behind a curtain in another room. Michele fires his shotgun, but the figure walks away without a scratch. Elisabetta is amused, as she believes the survivors will be punished.

Michele orders Lorenzo to find Giulia while he goes outside to find the figure. While tiptoeing around with his shotgun, Michele doesn't see the killer, who fires from the dark a speargun that impales Michele through his neck. Lorenzo finds Giulia dead in the bathroom, then Michele when he opens a door from outside. Scrambling to find guns, he starts off by finding ammunition. Putting a shotgun barrel to Elisabetta's throat, he demands the truth about the killer he suspects: she's not Charlie, but Charlie and Elisabetta's daughter, who Elisabetta gave birth to while she travelled abroad. Elisabetta pleads for mercy for her child, but Lorenzo refuses. He empties the shotgun, revealing the blanks Elisabetta loaded, then places live shells in it before turning out the lights. "Charlie", who Elisabetta warns about Lorenzo's shotgun, steps into view and takes off her mask: Carla is the killer. Lorenzo admits he knew from her body being the only one not recovered. She faked her drowning, delighted to have seen the whole family squirm from that point onward while she avenged her dead father.

When the sun comes up, Lorenzo marches the women to the motorboat at gunpoint. Elisabetta demands to know why Lorenzo didn't stop Carla when he figured her out, Lorenzo confessing he wanted his family dead anyway. Demanding the spark plugs back, Carla says she'll take Lorenzo to the location. She retrieves them, but then runs, Elisabetta stopping Lorenzo from chasing her. Lorenzo shoots Elisabetta and breaks from her grasp to run after Carla. Lorenzo catches up to Carla and shoots her dead, taking the spark plugs from her hand. However, Elisabetta dumps gasoline into the boat before she too dies. When Lorenzo tries to start the propeller, the boat bursts into flames, immolating him instantaneously.

• Arthur Kennedy as Ubaldo
• John Richardson as Lorenzo
• Caroline Laurence as Giulia
• Venantino Venantini as Valther
• Dana Ghia as Elisabetta
• Massimo Foschi as Michele
• Loretta Perischetti as Patrizia
• Flavia Fabiani as Carla
• Rita Silva as Greta

• List of Italian films of 1977

• Nine Guests for a Crime at IMDb