(Adapted for this production by stage director Lee Streby)
Sherman Oaks, CA, 1984. Two young popular senior sports jocks at Valley High School, Freddy and Billy, are boasting about the beauty and virtue of their girls, the “sister-babes” of the valley, Fiona and Bella. Their older friend: cynical, chauvinistic “Coach” Don Alfonso, declares that the girls’ loyalty to stick with their righteous dudes is “bogus” like the phoenix you hear about but no one has ever seen it. Coach Alfonso challenges the young athletes to a wager, if they’ll give him one day and do whatever he asks. Alfonso is confident he can prove the sisters will leave them - because in his many years of experience with the female sex – women are like that! Unwilling to believe the “sister-babes” would dare go to the prom with other guys, Freddy and Billy accept the wager, and Billy is so sure of himself on their virility, he increases the bet to one thousand, and the coach accepts.
At a “McMansion” nestled in a lovely Sherman Oaks subdivision, the wealthy Fiona and Bella return from aerobics class and are admiring their lovers pictures in the yearbook. They laugh and fantasize about love, sex, and marriage! (Duet: “Ah, guarda sorella”). Coach Alfonso arrives to begin his plot. He reveals devastating news: the young, star athletes have been recruited by the CIA to fly to Russia immediately as teen spies. Freddy and Billy appear at the house “heartbroken” and the four lovers make tearful farewells. As they leave in a clever ruse planned by Coach Alfonso, the boys miss their CIA helicopter and have to take a cab to catch up. The totally confused and weeping Fiona and Bella wish them a safe journey (Trio: “Soave sia il vento”).
The sisters’ family maid, Despina, enters with a tray of chocolate chip cookies prepared for the girls, complaining about how much work she has to do around the house. The girls enter and Bella vents her despair (“Smanie implacabili”). Despina refuses to take them seriously: they should simply find new lovers, since it is men who are unworthy of a woman’s fidelity (“In uomini, in soldati”). Fiona and Bella are shocked at her suggestion, after all, the two girls are among the most popular and beautiful girls in the San Fernando Valley! Coach Alfonso returns, and takes Despina aside to enlist her help, promising her a cut of his money if he wins, but not revealing the entire plot. Freddy and Billy enter shortly after as Alfonso’s friends from London, but Alfonso is stunned as he sees the two “foreign exchange students” in unplanned disguises; one transformed himself into a nerd and the other a punk rocker. Freddy and Billy, undaunted by the girl’s immediate reactions of fear and shock, approach the opposite friend’s “sister-babe” girlfriend. The sisters retreat, horrified, insisting the “freaks” leave immediately. Fiona sings proudly of her steadfast, unshakeable love for Billy, like a rock in a storm (“Come scoglio”). As the two young gentleman are jettisoned from the home, they gather outside the house to secretly celebrate their confidence at their alter-egos being rejected as a sign they could win the wager. Freddy expresses his love and trust in Bella. (“Un’aura amorosa”) before leaving.
In the finale, as the so-labeled “sister-babes” console their devastating news in lounge chairs by the pool when the ‘freak and geek’ pair of boys return. They pretend to have drank a mixture of poisons to fix their poor, rejected souls in love. Despina and Alfonso, watching closely, go off to fetch help, leaving the two girls to care for the strangers. Despina returns in disguise as a magical doctor “S. Nicks” famous for her special spell therapies. Doctor Nicks appears, and obtains the cure from a Magic 8 Ball before using a magnet to draw the poison from the boy’s quivering bodies. Once stable again, Freddy and Billy request kisses in order to fully recover. The sisters again reject them firmly, but with furtive glances unseen by their suitors, it is clear the young women are beginning to show curious interest in the visitors.
Despina lectures her mistresses on how to handle men (“Una donna a quindici anni”) and the sisters agree that there can be no harm in a little flirtation. They decide on which one to flirt with; obviously spurred by the curious sparks from their previous encounter, and choose each other’s boyfriend. Billy is left alone to spend time with Bella, and quickly manages to convince her to dispose of Freddy’s class ring to replace it with his own. Impetuously, Bella kisses him and the two stumble quickly off to make out (Duet: “Il core vi dono”). Freddy has the opposite luck in trying to soften Fiona’s feelings. But unknown to the teen, Fiona believes she may be falling for this sensitive “dweeb” after all.
Freddy, rejected again and excited that they have won the wager, returns to compare notes with Billy, who is reservedly happy to hear that Fiona has been faithful to him. But unable to keep the secret from his best friend, he shows Freddy the class ring he took from Bella in place of his own, making his friend furious. Billy, adopting Coach Alfonso’s philosophy, blames it on the women (“Donne mie, la fate a tanti!”). He asks Alfonso to pay him his half of the winnings, but Alfonso reminds him that the day is far from over.
Fiona reproaches her sister for her impetuous behavior, but Bella replies that love is a thief who only rewards those who refuse to steal a little (“È amore un ladroncello”). Alone and confused, in a final effort to maintain her resolve, Fiona enters suddenly with her own traveling clothes and plans to join the CIA Teen Spy progam. About to leave to surprise Billy in Moscow, Freddy appears. He tries one last time to seduce her and stop her from the dangerous plan, and finally succeeds. Fiona reveals she has the hots for him.
In an argument between the jocks later, Billy is furious that Fiona has fallen to Freddy’s advances, but in typical form, Alfonso states that they are simply powerless because this is the way women behave. Therefore, the boys are to learn a lesson: to be deceived by a woman he must only blame himself.
The sisters have agreed to attend the prom with the two foreign exchange students. The four appear at the school, where they encounter the school secretary Grace (once again, Despina in disguise) who requires them to review and sign a Nancy Reagan sponsored “Just Say No” Prom Promise Contract for proper behavior in order to obtain their tickets. As Fiona and Bella sign the contracts, Coach Alfonso gets a frantic phone call, followed by a taxi arriving outside the prom – it is Freddy and Billy, their "stud muffins" have returned, missions cancelled. Despina in her disguise crawls beneath a table to hide with the contracts.
The foreign exchange students leave to avoid confrontation with the “delisha-dudes” and hide in a small room. Moments later, Freddy and Billy walk through the front door in their same clothes and spy gear from the previous day. They happily embrace their original girlfriends. Noticing their girlfriends’ discomfort, they soon discover the prom contracts, tickets, and Despina, prom matron, hiding under the table. They immediately blame the girls for being fake, fickle Jezebels who don’t deserve their love and ask for their class rings back. Fiona and Bella struggle to explain, but end up in tears and hand over the rings. Alfonso announces with a sly wink that the proof of the girls’ betrayal are his friends from London in the next room. He tells the two young athletes they should never be surprised or disappointed because, once again: all women are like that. Freddy and Billy race into the next room to confront the “British” suitors. Moments later, they return with half of their disguises and half of their regular clothes.
As Fiona and Bella grasp what has happened, they cling to each other in horror. Not wanting to cause a scene at the prom, however, they follow along as Alfonso suggests they forgive their gentleman lovers for not understanding who they are. The girls accept the proper class rings back. Coach Alfonso, obviously uncomfortable, goes to the microphone and starts talking more about the philosophy of life, people can happy by accepting human behavior is often just inherent, and unchangeable. As he is talking, Fiona, Bella, and Despina are seen in a huddle behind the three men exchanging secrets. While the Coach rambles on, Fiona and Bella approach their lovers demanding they pay Coach Alfonso what they owe him and then leave, which they do.
Finally, Despina approaches Alfonso and holds out her hand for her half of the money. Alfonso dashes out of the gym. Despina, furious, races after him. Alone in the gym, Fiona and Bella embrace each other, and then hand-in-hand race after their lovers, but they are neither happy or sad. They're totally pissed, like, 'for sure!'