Lucy advertises for a roommate to help with the expenses, and after reading the correspondence, she finally decides on Carol Bradford (Carol Burnet), a frumpy off-kilter librarian. Carol soon starts taking over, reorganizing the apartment, laughing like a hyena, and generally driving Lucy nuts. Lucy and Mary Jane scheme to help Carol develop a social life (to keep her out of Lucy's hair), so they have a small party to introduce her to some boys. It isn't long before usually mild-mannered Carol begins drinking, singing, and being the life of the party.

Efficiency expert Oliver Kasten takes over Mr. Mooney's office and commandeers his secretary, Lucy Carmichael, who quickly patterns herself after Kasten, following his strict orders without question.

Lucy is preparing to go on vacation, but she has a change of heart when her substitute secretary turns out to be an attractive blonde who Mr. Mooney really likes. Lucy secretly doesn't go on vacation, and spies on them in various disguises.

Lucy finds a sale on beans that says ""The Best Beans You've Ever Eaten or Double Your Money Back"". Needing money for new furniture, Lucy & Mary Jane keep buying and returning more and more beans until they have collected $1,500.00! Little does Lucy know that Mr. Mooney is helping to sell them.

When a letter arrives from the US Government, Lucy finds that she's mistakenly been drafted. Instead of ""Lucy,"" the letter is addressed to ""Lou C."" So she sets off to the draft office to correct the mistake, but due to stupid ""rules and regulations,"" Lucy finds that she has to become a marine until the paperwork gets straightened out... So she does what any woman would do -- she makes life miserable for her Sargent.

Lucy is mistaken for a shoplifter called ""The Red Flash"" and taken to jail, but she thinks she's in jail because she littered a candy wrapper.

Lucy fakes sick so she can get out of work and accompany Carol, who's going to entertain at a golf tournament in Palm Springs. When they arrive, the hotel staff realizes that there's two women rooming together, so Lucy finds herself having to partake in the show. Lucy later weasels her way into an encounter with a distinguished actor, Collin Grant (Dan Rowan), and gets herself invited to a dinner dance. It's a good excuse not to go back to work when she finds that Mr. Mooney is Mr. Grant's partner in the golf tournament...

Lucy holds a protest against a freeway destroying a small town. The catch is that Mr. Mooney is helping to get the freeway.

Mr. Cheever warns Mr. Mooney that his job is in jeopardy unless he attracts new business to their branch of the bank. So when Lucy hears that a recording star, country hick Homer Higgins (Ernie Ford), is about to become a California resident, she sets off to the hotel to coax him into setting up an account with their bank. To impress Mr. Higgins and his family, Lucy and Mr. Mooney set up a hoe-down in the bank after it closes that evening...and Lucy decides to dress down to pose as Mrs. Mooney.

Lucy writes a jingle for a dog food company and wins a trip to London, England (""in Europe""). But when she misses her flight, she's forced to take a commuting flight to New York -- in a seat next to Mr. Mooney, who's on his way to the Big Apple for a business meeting.

Lucy and Mary Jane spend their lunch hour shopping for furs (despite the fact they only have 27 cents between them) so they can take advantage of the store's free tea and sandwiches. As they're getting ready to leave, the duo run into Pat Collins, a hypnotist, who says she's appearing at The Royal Club. Later at the bank, Mr. Mooney confides to Lucy that he has insomnia and hasn't slept in days, so she offers to take him to see Pat to cure him of his sleep deprivation. But Mr. Mooney has his reservations about being hypnotized, so he drags Lucy on stage with him...

George Burns arrives at the bank to pick up his statement, but Mr. Mooney has problems locating it. While waiting for Lucy to return to work, Mooney and Burns chat, and Mr. Burns reveals that he's having trouble finding another girl to be in his act. Enter Lucy, who goes on to explain her rather unique filing system, impressing George so much that he asks her to be his new comedy partner. The two go on to do a hit show and are offered a gig in Las Vegas, but Lucy declines, saying that she could never leave Mr. Mooney behind.

Mr. Mooney has a $6,000 ring delivered, which is an anniversary present for his wife. Lucy wants the thrill of having such an expensive rock on her finger for a brief moment, and Mooney obliges, only to find that the ring won't come off. Lucy reveals that she ""has a condition"" that causes her fingers to swell when she becomes nervous, so she takes some relaxing pills that the doctor prescribed her. But the pills make her loopy and knock her out, so Mr. Mooney spends the remainder of the day dragging Lucy's body around and trying to get her to wake up long enough to get the ring off. He finally gets her conscious, only to end up with the ring lost in the drain.

When Mr. Mooney sends Lucy to the movie studio to deliver some papers regarding the financing on John Wayne's new film, she ignores his warning not to bother Mr. Wayne and finds herself lunching with him. Nervous and excited, Lucy proceeds to talk his ear off and finally splatters him with ketchup. Mr. Wayne takes that as his exit cue, but Lucy soon tracks him to the set of his film, where she continuously screws up the production.

When Sheldon Leonard convinces Mr. Mooney to let him shoot a televison pilot at the bank, Lucy mistakingly thinks he is a gangster who plans to rob the bank, so she and Mary Jane sneak into the bank at night, disguised as scrubwomen, to stop them.

Lucy is overworked, between the work that she's neglected and having to sell tickets for a benefit for the bank. Mary Jane warns that Lucy will have a nervous breakdown if she's not careful, but Lucy initially blows off this comment -- but she later thinks she's been hallucinating when she enters Mr. Mooney's office and finds a monkey, who's part of the benefit show, sitting at Mooney's desk. Lucy thinks she's been seeing Mr. Mooney as a monkey, so it's off to the psychiatrist's office, who gives her this advice: ""Face your fear and it will disappear."" So on her next encounter with the simian, she treats him as if he's Mooney... which gets confusing as Mooney and the monkey simultaneously enter and exit the room...

Ventriloquist Paul Winchell comes into the bank and opens an account with Lucy. When Mr. Mooney fails to find a celebrity for an upcoming benefit for the bank, Lucy suggests that Mr. Winchell appear. But a mishap causes Lucy to have to stand in as the ventriloquist's dummy on the night of the show.

Recently married Vivian leaves Danfield to visit Lucy and the two begin gossiping and making up for lost time. When Viv tells Lucy about a friend's son who's now sporting long-hair, a guitar and a clock earring, the duo decide to dress up as hippies and set off to Sunset Strip to find ""Itchy"" to rescue him from the underworld. Lucy and Viv quickly find themselves in The Hairy Ape, where they finally find Itchy entertaining – after they spend the evening having to dance with the hip crowd.

Wanting a break from the bank and to make some extra money, Lucy visits an employment agency and lands a job as a babysitter. Little does she know that the babies are actually chimps!

Picking up where ""Main Street USA"" left off, Lucy, Mr. Mooney, and Mel Tinker stage a shootout at the bank for press coverage, to bring the freeway problem to the attention of the world.

When Lucy accidentally gets Mr. Mooney stationed on a submarine by talking too much, she sneaks onto the submarine dressed as a sailor to get him to sign some important contracts, but the submarine takes off before Lucy can exit.

Mr. Mooney has a fight with his wife, so Lucy decides to have some flowers sent over for her. When Eddie, the florist, arrives with the arrangement, Mr. Mooney immediately recognizes him as a former boxer. Eddie wants $3,000 to open up his own florist shop, but Mr. Mooney denies him a loan – so Lucy arranges for Eddie to partake in a boxing match to earn the money.