A BAY OF BLOOD

One night at her bayside mansion, Countess Federica Donati is attacked and strangled to death by her husband, Filippo, who stages the murder as a suicide. Shortly afterward, Filippo is stabbed to death by an assailant, who removes his corpse from the scene. Police find what they believe to be a suicide note written by the countess but fail to locate Filippo. Architect Franco Ventura travels to the property in order to have Filippo sign over ownership of the bay, unaware that Filippo has been killed. Filippo's daughter, Renata, and her husband, Alberto, travel to the bay with their two children to determine Filippo's whereabouts.

Four gallivanting friends—Luca, Roberto, Sylvie, and Louise—trespass on the property and break into the seemingly deserted mansion. Louise goes skinny-dipping alone and encounters Filippo's corpse in the bay. While seeking the rest of the group, Louise is pursued and murdered by an assailant with a billhook. The assailant also uses the billhook to murder Roberto, then impales Luca and Sylvie with a spear while they have sex.

Alberto and Renata meet an eccentric entomologist named Paolo Fossati and his fortune teller wife, Anna, from whom they learn about Simone, the countess's illegitimate son, who lives by the bay as a fisherman. Alberto and Renata question Simone about Filippo and discover Fillipo's corpse in Simone's boat, though Simone says that he found the body in the bay. Alberto leaves Renata at Ventura's cottage while he gets their car. Renata discovers the bodies of Luca, Roberto, Sylvie, and Louise in Ventura's bathroom. Ventura attacks Renata with an axe, but Renata stabs him with scissors and leaves him for dead. Paolo and Anna separately discover the bodies at Ventura's cottage and are killed by Alberto and Renata before they can alert the police.

Ventura's secretary and lover, Laura, arrives at Ventura's cottage. She discovers that Ventura is wounded, and he tells her to bring Simone. At his cabin, Simone accuses Laura of conspiring with Ventura and Filippo to kill the countess. Laura confesses that Ventura had her seduce Filippo, but falsely claims that she did not know that Filippo would kill the countess. Simone strangles her to death. It is revealed that Simone killed Filippo, Louise, Roberto, Luca, and Sylvie, and that Ventura convinced him to sign away the property for a payoff, airline tickets, and a fake passport. Alberto and Renata follow Simone from his cabin, and Alberto kills him as part of the couple's plan to obtain the property. The couple returns to Ventura's cottage, where the still-alive Ventura attacks Alberto, who kills him after a struggle. Alberto burns the documents signed by Simone and Ventura.

Alberto and Renata prepare to return home to await the announcement of their inheritance when they are shot dead by their son, who has mistaken their shotgun for a toy. The son and daughter think their parents are playing dead and rush outside to play along the bay.

Alberto and Renata eliminate their rivals to secure the inheritance, only to be shot dead by their son, who mistakes a shotgun for a toy.

The ending subverts expectations, showing that the cycle of violence spurred by greed ultimately leads to senseless tragedy. The child’s fatal mistake underscores the film’s blackly comic tone and its bleak perspective on the consequences of unchecked ambition.