The year is 1661 and London is celebrating the Restoration and the fall of Puritan Austerity. Morals have slipped. Just the climate for Horner, a handsome libertine, who just can't resist women! the local populace are fearful of Horner, and are plotting his comeuppance (Lust). However, Quack, a physician, who derives great pleasure from the sexual antics of Horner, plans a grand deception to help him (The Art Of Deceiving).
While Horner is is cooling his heels in France, Quack has been spreading a rumour around London society, that Horner has caught the "pox" there and have been castrated (Serve The Dog Right).
The women are devastated but the men are delighted, and enjoy the happy hour at the local tavern, making the most of the news of Horner's condition. Horner, having heard Quack's plan on his return, is delighted and plays along with the ruse (A Pox On Love And Wenching).
Meanwhile, Pinchwife, an embittered victim of Horner's - he once bedded his future bride on the eve of their wedding - has returned to London with his beautiful new 'country wife' Margery. He returned in order to marry off his spinster sister Alithea to the odious Sparkish, an effeminate fop, greedily waiting to receive the large dowry.
Ignorant of Horner' assumed predicament, he fears for his wife's safety, after Horner declared this love for Margery (having seen her at the theatre the previous evening) and confines her to their lodgings.
Margery, overjoyed at hearing this, but nevertheless very upset at not being able to go to the theatre again, indulges in fantasy (Somewhere Out There).
Alithea meets Harcourt, a more presentable young man, at the theatre that night and they are immediately drawn together.
In another part of London the 'ladies of quailty' are discussing the shocking news about Horner, and declare their own concerns at the state of moral decay among the upper classses, at the same time hiding their own shortcomings (Ladies of Quality).
Sir Jasper, husband to Lady Fidget, is keen to keep his wife happy while he plays away, and offer the services of Horner for this purpose, naively assuming that he is functuous officio!. Quack warns (Husbands Beware).
Margery is most disgruntled at being locked up, and warns Pinchwife that she will cut off his conjugal rights if he does not take her to the local hanging, where she would secretly like to meet Horner, after his declaration of love.
Pinchwife agrees, but only if she dresses as a man, and poses as his brother! Margery agrees. Horner and the other men attending immediately guess she is his wife in disguise (What A Handsome Little Fellow).
Livid at her behaviour at disappearing into the night with Horner, Pinchwife demands that Margery write him a letter, abusing him, which he dictates (Dear Sir).
Horner, having declared to the world that he is officially a eunuch, is having a whale of a time bedding the ladies (Ode To The One I Love).
However, he is caught red handed with lady Fidget by Sir Jasper who is fooled into thinking that his wife visits Horner to help her choose pieces of China for her collection! (China). Margery, Harcourt and Alithea are in love and bemoan their predicament (Come Tomorrow). Horner, in a state of exhaustion, still cant get Margery out of his mind.
Having received her love letter he is comforted by his friend and confident Quack, who suggests he spends some time 'in the country' (A Little Time In The Country).
Margery gets herself into further trouble with Pinchwife, by writing yet another letter to Horner.
She declares that she is writing it for Alithea, who is, she says, in love with Horner, who has proposed marriage.
Pinchwife is pleased at this, as he could possibly save paying the dowry money to Sparkish. He does insist though, that he will take Alithea and a Parson to see Horner and deliver the letter.
However, as Alithea has no knowledge of this, Margery disguises herself as Alithea and even wears a mask! Margery meets Horner. Pinchwife goes to fetch the parson. Horner gives Margery (The Master Class).
Problems arise. Three 'ladies of quality' have come in to straighten out their position with Horner, having discovered that he has bedded all three! (One Of You)
Horner has to finally prove to the disgruntled husbands that he is truly a eunuch, which he does with a little help of his dear friend Quack. (We Thank You / Lust).