Lust for Revenge (1976)

Seeking inspiration for his unfinished novel, a blocked writer talks his bored friends into playing a cruel game. Intrigued by their host's exciting but risky proposition, the jaded thrill-seekers abduct the innocent daughter of an unsuspecting couple on a summer holiday for kicks. But as the desperate parents pull the strings to come up with the enormous ransom for the return of their little girl, an unforeseen complication leads to unbridled violence and murder. How far is a father prepared to go when he lusts for revenge?