Plot

A Hollywood composer endures a mid-life crisis and becomes infatuated with a newly married woman honeymooning at a Mexican resort.

Forty-two year old famed composer and playwright George Webber (Dudley Moore) is going through a midlife crisis. He is seriously dating thirty-eight year old actress and singer Samantha Taylor (Dame Julie Andrews), who he loves, although he admits their connection is more intellectual than it is emotional. She, in turn, loves him, despite barely tolerating his often infantile behavior. This behavior includes spying on a neighbor's sexual encounters with a wide array of women, this spying about which the neighbor knows, as he does it himself. Driving one day, George spots a young woman who he believes is the most beautiful creature he's ever seen - an "eleven" on a scale of ten, tens which he didn't believe existed before her. Beyond the fact that she is probably half his age, a problem with George's infatuation is that she is just off to her own wedding. George and Sam's relationship takes a hit with an argument which is further exacerbated by a series of misunderstandings. As such, George decides to pursue the woman of his dreams with all of his energy. He learns her name is Jenny Miles, now married Jenny Hanley (Bo Derek), and he is able to follow her to a Mexican resort where she and her husband David Hanley (Sam J. Jones) are honeymooning. In his pursuit of Jenny, his encounter with a lonely woman named Mary Lewis (Dee Wallace), who is vacationing at the resort, and his discussions with his gay lyricist Hugh (Robert Webber) concerning his relationship with his much younger trophy husband Larry (Walter George Alton), George may come to a clearer picture of what he is doing in Mexico, and how he truly feels about Sam.—Huggo

A successful, middle-aged Hollywood songwriter falls hopelessly in love with the woman of his dreams, and even follows the girl and her new husband to their Mexican honeymoon resort. While his behaviour seems sure to land him in trouble, out of the blue fate plays into his hands.—maschzentertainment

On the night of his 42nd birthday, George Webber (Dudley Moore), a popular songwriter, begins showing symptoms of a "middle-age crisis". Over the succeeding weeks, he finds himself continually staring at young girls on the street, and he begins envying his high-living neighbor, whose life is one endless orgy. George's behavior causes great concern to his lover, singing star Samantha Taylor (Dame Julie Andrews), and to his partner Hugh (Robert Webber), who has seemingly avoided George's dilemma by being gay. While driving home one afternoon, George spots Jenny Hanley (Bo Derek), a stunning young beauty en route to her marriage ceremony. Regarding her as "the most beautiful girl I've ever seen" (on a scale from one to ten), George follows her to the church. He later learns her name, and discovers that she and her husband are honeymooning in Mexico. Driven by the impulse to see her again, George flies to Mexico and checks into the hotel where Jenny is staying. Later, he sees the couple on the beach, and begins indulging in romantic fantasies about the lovely young girl. When he rescues her husband from drowning, a grateful Jenny invites George to her room.—alfiehitchie

During a surprise 42nd birthday party for George Webber, a well-known composer of popular music, he finds himself coping badly with incipient middle age. When he catches a glimpse of a mysterious woman en route to her wedding, he is instantly obsessed by her beauty, and - despite the presence of his lover Samantha Taylor - follows the woman to the church where he crashes into a police cruiser and is stung by a bee. George visits the priest, and learns that the woman is Jenny Miles, daughter of a prominent Beverly Hills dentist. Later that night, Sam and George have an argument about George's failure to give her the attention she needs, his use of the term "broad", and the fact that he and his neighbor (a wealthy porn producer) watch each other perform carnal acts using telescopes. The final straw for Sam occurs when George makes a remark subtly impugning her femininity at which point Sam leaves in a huff.

The following day, George and Sam suffer a series of mishaps that prevent them from reconciling, including George spying on his neighbor until hitting himself with his telescope and falling down an embankment, causing him to miss Sam's phone call. In addition, George schedules a dental appointment with Jenny's father, and while in the dentist's chair, subtly leads the dentist into disclosing that his daughter and her husband went to Mexico for their honeymoon. The examination also reveals a mouthful of cavities, requiring the dentist to spend the entire afternoon inserting fillings in George's teeth. The after effects of the novocaine, which are aggravated by his heavy drinking immediately after, leave him completely incoherent and when Sam finally reaches him on the phone she mistakes him for a madman and calls the police. The police storm his house, but recognizing him they leave amicably. He visits his neighbor's house to take part in an orgy just as Sam arrives at his house, and she spots him through his telescope, widening the rift between them.

Later, George impulsively follows the newlyweds to their exclusive hotel in Manzanillo, Colima, Mexico. In the bar, George encounters an old acquaintance, Mary Lewis, who suffers from a lack of self-confidence because she blames herself for a series of failed relationships. When they attempt a fling that night, she interprets George's inadequacy in bed as confirmation of her insecurities despite her better-than-average looks and easygoing disposition.

One hot day at the beach, George sees Jenny - suntanned and dressed in a one-piece swimsuit and her hair braided in cornrows - which furthers George's obsession. He notices that David, Jenny's husband, has fallen asleep on his surfboard. Pretending to inquire about renting a surfboard, George learns that beyond a certain point are powerful currents that can sweep a swimmer or surfer dangerously far from land. George rents a catamaran, clumsily but successfully rescues David, and becomes a hero. Both Sam and his songwriting partner see him on TV Network News and Sam tries to call him, but George (unaware that it is Sam) refuses the call. David, badly sunburned, stays in the hospital, allowing Jenny and George to spend time alone together, culminating in Jenny seducing him to the sounds of Ravel's Boléro.

Although George is initially elated to find all of his fantasies being fulfilled, he is horrified when Jenny takes a call from her husband while in bed with him and casually informs him of George's presence. He is even more confused when David responds with a complete lack of concern (he had called to thank George for saving his life). When Jenny explains their open relationship and mutual honesty, George is appalled; with the thrill of enjoying forbidden pleasures extinguished, he loses interest in Jenny (Jenny, for the opposite reasons, loses interest in him as well) and he heads back to Beverly Hills.

At the end of the film, he reconciles with Sam by demonstrating a new maturity and, taking an idea from Jenny, he starts Ravel's Boléro on the phonograph and they make love with the music playing in the background. This is in full view of the neighbor's telescope shortly after the neighbor has walked away in disgust, complaining that he has had enough of providing erotic entertainment to George and getting nothing in return.