Scene 1: J. Pierrepont Finch, a young window washer with large ambitions, is at work on the windows of the World Wide Wicket Company. He has a squeegee in one hand and a copy of the book How to Succeed in Business Without Really Trying, in the other. A disembodied voice (the voice of the book) announces that from the books lessons, Finch will learn everything he needs to know to get ahead. Excited, Finch sings the titles of chapter headings in the book (How to Succeed in Business Without Really Trying") as his scaffold descends. He removes his overalls, under which he is wearing a business suit, and steps into an office tableau.
Scene 2: After accidentally knocking down J.B. Biggley, the feared president of the company, Finch announces he'd like a job. Biggley stuffily refers him to the personnel manager. Rosemary Pilkington, a secretary, is impressed by Finch's boldness. She offers to help him meet Mr. Bratt, the personnel manager, who initially treats Finch brusquely, warming only at the mention of Biggley's name. Finch ingenuously implies that he and Biggley are old friends, causing a marked change in Bratt's attitude. Finch is promptly given a job in the mailroom. One of his fellow workers is Mr. Biggley's nephew, Bud Frump, who never hesitates to use his familial position to get ahead. Rosemary, who dreams of married life in the suburbs with an executive, has taken a liking to Finch, and fantasizes about him to her friend Smitty ("Happy To Keep His Dinner Warm").
Scene 3: A coffee break is called, but the machine has run out of coffee. The caffeine-addicted office workers begin a frenzied dance ("Coffee Break"). Finch feels frustrated at having been at the company for a whole week without discernible advancement. Through Rosemary, Finch meets Miss Jones, Biggley's secretary. He flatters her and makes sure to put in a bad word against Bud Frump.
Scene 4: Twimble, the head of the mailroom, is moving to the shipping department and must choose his successor. He explains to Finch that a lack of ambition, a fear of being fired and an absolute trust in the company's wisdom have kept him happily in the mailroom for 25 years ("The Company Way"). He announces that Finch is his choice to head the mailroom. Finch - as per the book's careful instructions - insists that Bud be given the job instead, for the good of the company. This impresses Twimble and Bratt, and Bratt offers Finch a job as a junior executive in the Plans and Systems Department, which is headed by Gatch. Realizing he has been outmaneuvered, Frump fumes.
Scenes 5 and 6: Biggley arranges a secretarial job for his beautiful mistress, Hedy La Rue, formerly the cigarette girl at the Copa. Her entrance attracts the attention of all the men in the office, prompting Bratt to explain the office policy on flirting ("A Secretary is Not a Toy").
Scene 7: It is late Friday afternoon, the end of the work week. As they wait for the elevators, the secretaries complain of unwanted attention from their male bosses, while the men talk of sales figures. The ever-attentive Finch discovers that Mr. Biggley is a proud graduate of Old Ivy. He also learns Biggley will be returning to the office Saturday morning to retrieve his golf clubs for a game with Wally Womper, the Chairman of the Board. Rosemary arrives at the elevator with Smitty, who knows that despite their awkward silences, Rosemary and Finch like each other ("Been a Long Day"). Smitty recommends a dinner special for two at a nearby restaurant, and Rosemary and Finch decide to take advantage of it. After they leave, Bud Frump runs into Hedy and Biggley, who are arguing about her job. Bud surmises the nature of their relationship and threatens to tell his mother, Biggley's sister-in-law, if Biggley doesn't guarantee him a promotion (Reprise: "Been a Long Day"). Biggley is trapped and Frump, like Finch, is on his way up the corporate ladder.
Scene 8: It is Saturday morning. Finch, knowing Biggley is coming to retrieve his golf clubs, shows up at the office before Biggely arrives and creates a mess to suggest he has been working there all night. When Biggley arrives, Finch begins "absent-mindedly" humming Old Ivy's fight song, suggesting to Biggley that they are both Old Ivy graduates ("Grand Old Ivy").
Scenes 9 and 10: Biggley demands Finch be given his own office and secretary. Bratt assigns Hedy La Rue to him. The book has warned him about just such inadequate secretarial help - Hedy has many skills, but typing and shorthand aren't among them. When Finch discovers Biggley is Hedy's sponsor, he sends her to Gatch on an errand, knowing Gatch will make a pass at her. Soon Finch is sitting at the desk of the now Venezuela-bound Gatch.
Scenes 11 and 12: Rosemary hopes to win Finch over with her new dress, a Paris original, at the reception for new Advertising Department head Benjamin Burton Daniel Ovington. When she arrives at the party, Rosemary sees that every woman there is wearing the same dress ("Paris Original"). Hedy has too much to drink, and Biggley orders Bud to take her home.
Scenes 13 and 14: Hedy goes up to Biggley's office to take a shower. As she showers, Bud tells Finch that Biggley is waiting to see him there. Bud goes off to find Biggley, hoping to trap Finch with Hedy. Hedy finds Finch in the office and makes a play for him, but when she kisses him he realizes he loves Rosemary, who enters as Hedy returns to the bathroom. Finch proposes to her ("Rosemary"). As Rosemary is about to accept, Hedy comes out of the bathroom in a towel. Rosemary angrily leaves the office, but returns to announce that Bud and Biggley are just outside the door. Hedy goes back into the bathroom, and Finch and Rosemary embrace as Biggley enters the room - Bud's plan is foiled. Bratt and Ovington enter, looking for Biggley. Ovington is forced to resign after Finch prompts him to reveal that his alma mater is the arch-rival of Old Ivy. Biggley then makes Finch Vice-President in Charge of Advertising, just in time for a big strategy meeting two days later. Biggley departs, leaving Finch and Rosemary alone again. They declare their love for each other as Bud vows to stop Finch's meteoric rise ("Finale - Act One").
Scene 1: It is the morning of the big meeting. Rosemary, feeling neglected by Finch, has decided to quit. Smitty and the other women in the office convince her that she can't quit and remind her that she's living their dream of marrying an executive ("Cinderella, Darling").
Scene 2: Finch is quite pleased with his promotion, though the book sternly warns that this new advertising job is a dangerous position. However, as long as he already has the job, the book suggests that the one way to save his situation is to come up with a good idea. Unfortunately, Finch doesn't have one. The book forsees this and suggests that he steal someone else's. It is at this moment that Bud Frump approaches him with the idea for a televised treasure hunt. Delighted, Finch adopts the notion, unaware that Biggley has already heard the idea and shot it down. Finch tries the idea out on Rosemary, who responds by telling Finch she loves him (Reprise: "Happy to Keep His Dinner Warm").
Scene 3: Hedy, unhappy with her secretarial duties, announces to Biggley that she is quitting. Biggley pleads with her to stay ("Love From a Heart of Gold").
Scene 4: In the executive washroom, Bud assures the other executives that Finch's presentation will flop and end his rapid rise in the company. Finch enters and gives himself a pep talk before the meeting as he washes his hands ("I Believe in You").
Scene 5: Finch presents his idea for a televised treasure hunt/give-away: he will hide five thousand shares of company stock in each of the ten company offices around the country, and give the audience weekly clues as to their whereabouts. Biggley doesn't like the idea until Finch explains that each week's clue will be given by the scantily- dressed World Wide Wicket Treasure Girl, Hedy La Rue.
Scene 6: During the first television show, Hedy, as the Treasure Girl, is asked to swear on a Bible that she doesn't know the location of the treasure. She can't lie: the previous night Biggley told her the treasure is located in each of the ten company buildings - a fact she relates to the entire television audience.
Scenes 7 and 8: Eager treasure hunters have wrecked the World Wide Wicket office, and the executives, including Chairman of the Board Wally Womper, are waiting in Biggley's office for Finch to appear to hand in his resignation. Rosemary, told by Finch that he'll probably have to go back to washing windows, assures him she'll still love him just as Bud arrives to take Finch up to the office.
Scene 9: Finch, about to sign his letter of resignation, reveals he was a window washer before coming to the company. This immediately draws the admiration and trust of Womper, also a former window washer. Finch adroitly places the blame for the give-away show on Bud. He also tells Womper that Bud is Biggley's nephew. Womper is about to fire all the executives when Finch convinces him to spare them, telling him that everybody is part of the human family ("Brotherhood of Man"). Bud Frump, however, is fired and escorted out of the office.
Scene 10: The show ends with the announcement to the employees that Biggley is still the president, that Womper is retiring to travel the world with his new wife, Hedy, and that the new Chairman of the Board is Finch. Finch calls Rosemary to his side as he starts to think about capturing the Presidency of the country. Outside, Bud Frump is seen on a window-washing scaffold, reading How to Succeed in Business Without Really Trying ("Finale").