The action is set in Bath, England, in 1775. Wealthy and beauteous Lydia Languish has spurned dozens of suitors only because they were rich. She longs for a poor husband who will love her for herself, not her wealth. Debonair and roguish Jack Absolute loves Lydia. Knowing that she wants an impoverished spouse, he is masquerading as Ensign Beverly, a nautical pauper. Lydia spells out to her adoring Jack her hopes for an indigent husband. In his responses to her, Jack covers up his skepticism regarding Lydia's romanticization of poverty (POOR).
Lydia's maid, Lucy, dreams only of a rich and handsome husband. While walking down a street in Bath in the company of her fellow servants, she passes and briefly notices the fiery Irish noble Sir Lucius O'Trigger. She is immediately certain that Lucius is her man (WHAT CAN IT BE?).
Fat and foppish Bob Acres, a longtime suitor of Lydia's, is also a close friend of Jack Absolute. Never realizing that his friend is his secret rival, Bob unburdens to Jack his troubles with Lydia. As Acres ponders his rival "Beverly," his consternation turns to wrath and he spouts a torrent of cursing, in his particular style. Bob demonstrates to Jack his unique method of swearing and encourages Jack to try his hand at it (ODDS).
Sir Anthony Absolute, Jack's father, is determined that his son should marry Lydia. Jack fears that his father will prematurely disclose his disguise to Lydia and thereby destroy Lydia's love for him. While pondering how to outwit his impetuous father, Jack admits to himself that he loves Lydia in spite of her lack of intelligence (I LOVE A FOOL).
Lydia's aunt and guardian, the notoriously verbose Mrs. Malaprop, plots with Sir Anthony to bring the two young people together. While discussing their mutual problems, Mrs. Malaprop extols the virtues of her niece. She boasts of her clearly ludicrous efforts to make Lydia a lady of excellent linguistic ability, prompting the appalled Sir Anthony to insist that a well-educated woman can be a deterrent to a happy marriage (A MORE THAN ORDINARY GLORIOUS VOCABULARY)
Sir Anthony finally finds his elusive son. They argue over Sir Anthony's abortive attempt to bring about a romance between his son and Lydia. Sir Anthony attempts to persuade his reluctant son that Lydia more than deserves his love (THE LADY WAS MADE TO BE LOVED). As soon as Sir Anthony leaves, Jack echoes his father's praise of Lydia.
Meanwhile, Bob Acres encounters Sir Lucius, telling the hot-blooded young Irish noble about his hated rival, Ensign Beverly. O'Trigger demands that Acres challenge his rival to a duel, impressing upon him that fighting the duel will save his honour (HONOUR). Shortly after this, O'Trigger and Sir Anthony have a run-in. O'Trigger challenges Sir Anthony to loaded pistols at 80 paces on the same morning and same field as he suggested to Acres for his duel with Ensign Beverly.
Lucy, the maid, has been saving the money she receives when passing messages from lover to lover. She appears on the street in Bath, gowned in the highest fashion, causing her fellow servants to gather. When Sir Lucius passes by, Lucy several times drops the books she is carrying, forcing him to politely pick them up and notice her. She is convinced that he will be hers (I FOUND HIM). Her fellow servants remind her that maids don't marry into the nobility (DAY DREAMS).
Lydia and Ensign Beverly have a rendezvous, during which she begs him to tell her how much he loves her. Taken aback by her brashness, he suggests that it's better not to ask him to be too specific about anything beyond the fact that he loves her (DON'T ASK ME). Sir Anthony and Mrs. Malaprop discover the lovers and reveal to the horrified and hurt Lydia that Ensign Beverly is really the wealthy son of Sir Anthony.
To drown his sorrows and forget his woes, Jack storms into a brawling brothel, where he meets O'Trigger and a trio of grenadiers. O'Trigger and his companions tries to cheer up Jack (WHY WIVES?).
Meanwhile, Mrs. Malaprop, Lydia and Lucy learn of the impending duels scheduled for that morning. They rush to the dueling grounds to stop the first duel between Bob and Jack.
All's well that ends well. Lydia and Jack make up. Lucy reveals that she has bought Blunderbuss Hall, the baronial home of the now-bankrupt playboy, Sir Lucius. Mrs. Malaprop, forlorn since she has long imagined that Sir. Lucius might be hers, is saved from solitary old age by the extended arm of Bob Acres. (ALL IN LOVE—FINALE).
(Adapted from the synopsis included with the cast recording on Mercury Records.)