A liberal-thinking author watches his wife as she attempts to seduce his best friend at a dinner party. She ends up taking on another man as well, and the writer has an affair with the another dinner guest. Soon the three men and two women are entangled in a confusing series of partner-swapping sex sprees where everyone's morals are challenged in the wake of the sexual revolution.

Hoping to shake up the complacent Italian Communist Party, a group of leftist radicals sends an incendiary letter to a major evening newspaper declaring their intention to volunteer to fight American troops in Vietnam as a political statement against the war.