It's the 21st century, and the dominant worldwide cultural interest is The Big Game, an organized murder system with hunters, victims and prizes. The rules are strict, and killing the wrong person will get you 30 years in prison, but the promoters of the game insist that by channeling mankinds violent tendencies into a regulated sport, wars will be avoided. After successful kills, a pair of ace hunters, Italian Marcello Polletti (Marcello Mastroianni), and American Caroline Meredith (Ursula Andress) square off in a battle of wits. Shes a cold-blooded pro who felled her last opponent with a double-barrelled brassiere; he's in the throes of an annullment while fending off marriage demands from his longtime amante, Olga (Elsa Martinelli). Each contestant is approached by advertisers wanting to make their next kill the centerpiece of an ad campaign: Caroline tries to trick Marcello into a trap set just outside the Coliseum, while Marcello plots to get Caroline into a pool so cameras can record her being eaten by a crocodile, while he recites his advertisers product slogan.