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While doing research for a documentary, filmmaker Bob Sanders takes his wife, Carol, to an Esalen-type "sensitivity" institute in Southern California.  Enlightened by the experience, the couple vow to expand their capacities for love and understanding by sharing everything with each other.  So great is their enthusiasm that they decide to share their newfound "liberation" with their closest friends, lawyer Ted Henderson and his wife, Alice.  But the Hendersons, particularly the somewhat inhibited Alice, remain skeptical.

Following a trip to San Francisco, Bob confesses to his wife that he had a brief extramarital fling with his production secretary.  Deeply moved by Bob's frankness and trust, Carol repeats Bob's confession to Ted and Alice, but the revelation leaves Alice so aghast that she feels compelled to visit a psychiatrist to discuss her sexual life with Ted.

Upon returning from another trip, Bob finds that Carol spent the previous night with Horst, the tennis instructor from their club.  Stifling his initial hostility in favor of a more "civilized" attitude, Bob insists that Horst sit down and join him in a friendly drink.  A short time later Bob and Carol and Ted and Alice go off to Las Vegas for a weekend.  Before leaving to catch Tony Bennett's dinner show, Bob relates Carol's experience with Horst, and Ted is moved to admit that he, too, recently indulged in a brief adulterous episode.

Unhinged by what has happened, Alice defiantly demands that they have an orgy before going out to dinner.  After some hesitation and discussion, the two couples agree to the proposal and all four climb into one large bed.  Despite some preliminaries, however, they find that they are unable to go through with it.  Filled with good will toward each other, Bob and Carol and Ted and Alice get dressed, leave the hotel, and join the throngs of people milling about outside.