Five Dolls for an August Moon (1970)

A rich playboy invites a circle of affluent friends to his secluded beach estate for a leisurely weekend. As tension rises, the gathering takes a dark turn when one by one, guests begin to turn up dead. Panic ensues as the group realizes a murderer lurks among them, forcing them to unravel the mystery of the killer's identity before they become the next victims. With paranoia escalating, trust erodes, and the idyllic getaway becomes a deadly game of survival.