EYEBALL

Alma Burton, whose marriage to Mark, the owner of a marketing company in Vermont, is on the verge of divorce, is supposed to go to a mental institution in New York for treatment. However, at the airport she changes her plans at short notice and travels to Barcelona.

While in the Spanish city, a tour group of American tourists, which includes the secretary Paulette Stone, the lesbian photographer Lisa Sanders and her model girlfriend Naiba, as well as several wealthy entrepreneurs, are exploring Barcelona's sights by bus. However, the traveling party is soon shaken by a gruesome incident: the mysterious murder of a local woman. The victim, a young girl, is brutally killed by a murderer wearing a red raincoat who also gouges out her left eye. Soon after, the attractive American Peggy becomes the unknown serial killer's next victim, causing consternation among the travelers.

The aging Inspector Tudela, who is in his last week of work before retirement, takes over the investigation together with his young successor. The police are initially in the dark, but soon suspect that the perpetrator is in the group's environment, so that each of the travelers is formally classified as a potential murderer.

Mark Burton also soon joins the group, which includes his secret mistress, Paulette Stone. However, the series of murders does not stop, and Mark briefly fears that his unstable wife could be the murderer, as he once found her lying on the ground next to him with a bloody knife and one eye in her hand. He kept this incident quiet at the time and even covered up the traces so as not to endanger his marriage. He secretly thinks his wife Alma, who he currently suspects is somewhere in Barcelona, is a suspect. He initially kept this fact secret from the authorities.

Shortly after, Lisa Sanders is murdered, but before her death she manages to take an incriminating photo of the serial killer: Paulette, while Naiba interrupts the attack so that Paulette, contrary to previous crimes, does not mutilate her victim. Nevertheless, the series of murders does not stop and the number of tourists continues to decline until the serial perpetrator is caught red-handed at the end of the film. In the presence of Naiba and Mark, the inspector fatally injures Paulette, armed with a knife. It is revealed that her left eye is missing due to an accident when she was a child, hence her mutilation of the murder victims.

In the last scene of the film, the young inspector congratulates his experienced predecessor, who managed to solve the delicate series of murders within a week. Mark also makes a conciliatory phone call to his wife Alma, whom he gives another chance to save his marriage.

The killer is revealed as Paulette, who is fatally injured by the inspector in front of witnesses. Her motive is tied to her own missing left eye, and Mark reconciles with his wife Alma after the case is solved.

Eyeball concludes with the inspector catching Paulette in the act; her own childhood trauma and missing eye explain her signature mutilations. The resolution brings closure to the harrowing tourist ordeal and allows Mark to mend his fractured marriage, tying up the psychological and literal loose ends. The film lands as both a shocking whodunit and a portrait of obsession, wrapped up with a wink to the giallo tradition.