SCORE

In the mythical European city of Leisure, married couple Jack and Elvira have an ongoing bet regarding who can seduce whom. This comes up in the wake of a swinging night with a couple of tourists picked up via a newspaper ad. Elvira, a self-professed "sexual snob" has bet she can seduce newlywed Betsy, married to handsome marine biologist Eddie. If she fails by midnight, then Jack gets to seduce Eddie.

While Jack and Eddie go to work separately, Betsy comes round to visit her new friend Elvira. She's very intrigued by Elvira's open admission of her swinging lifestyle, including spouse-swapping and drugs. When Mike, the telephone repair man, arrives (Elvira had sabotaged the phone earlier just in hopes of a handsome man showing up), Betsy is fascinated and shocked as Elvira seduces him right before her eyes. She also admits that she's not really happy, especially after catching Eddie masturbating in the bathroom. But she says Elvira's actions are not for her, because at heart she is still a Catholic schoolgirl. Elvira tells a story about Jack, just before they were married, and how he said he would "climb aboard a porcupine" if he had a mind to.

The two couples get together that night, and get slightly high on pot. Pulling out a trunk of costumes, they decide to play dress up. Jack dons a sailor's uniform while Betsy wears a very revealing modeling outfit. To Betsy's shock/titillation (and Jack's huge amusement), Elvira's costume is based on a nun's wimple, but with nothing underneath. They tease Eddie into putting on a cowboy outfit.

As the night progresses, the two wives and two husbands pair off to wander and chat. During the course of their conversations, each of the naive couple admit to dissatisfaction, including a questioning whether they ever should have gotten married. Eddie, it turns out, was Betsy's brother's best friend. There is a hint that he and Eddie were maybe closer than friends, although Eddie doesn't seem to know that Betsy might realize that. Betsy, meanwhile, lets her hair down and is even a little worried something might "happen" between her and Elvira. She also gets giddy at saying the word "fuck" for the first time. Downstairs, Jack remarks to Eddie that just before he and Elvira were married, she commented, "Jack, I'd hop in the sack with a porcupine if it struck my fancy."

Elvira and Betsy end up in the upstairs bedroom, with Jack and Eddie in the downstairs den. A quick phone call between the swinging couple has them agree that midnight is the deadline for them both. As the late night progresses, both introduce their perspective seductees to amyl nitrite (each says the same line as they do: "Bingo!") and when asking for the time, interpret the respective watches as either "slow" or "fast" depending upon their own desires.

Both Eddie and Betsy are simultaneously seduced, receiving and giving oral sex. Betsy is even penetrated with a strap-on (while wearing a collar and leash). Eddie, penetrated by Jack, has a brief hallucination that the person making love to him is Betsy.

In the morning, Jack and Elvira consider the score pretty much even. Betsy and Eddie are confused, each thinking perhaps the other is the "normal" one. Betsy even makes a remark about them both being "porcupines." When Mike suddenly arrives for a visit, just as Jack and Elvira are getting ready to have a ménage à trois with Betsy, Jack invites him, too, boasting that they "play all kinds of games around here". A chance remark brings out the fact Mike and Eddie both enjoy bowling. Somewhat to Jack and Elvira's surprise, Mike leaves to play with Eddie and Betsy, who suggests they all get together soon to play "Bingo".

Both Elvira and Jack succeed in seducing Betsy and Eddie, respectively, culminating in a night of sexual exploration and partner-swapping.

The film’s conclusion delivers on its setup: the couples embrace experimentation, crossing boundaries in both heterosexual and homosexual encounters. By the end, the seduction bets result in everyone’s desires fulfilled, suggesting that curiosity and openness can dissolve conventional relationship limits. Metzger’s finale underscores the playful, nonjudgmental tone that runs throughout, with the film ultimately celebrating personal liberation and the joy of shared experiences.