Jack sups at a chichi nightclub where heartthrob crooner Robert Goulet is dining. Will Goulet pilfer Jack's drop-dead gorgeous date or will the sex symbol comic pull women away from Goulet? Two versions are presented. Which one is true?
Jack's guest is 6'6" Western star Clint Walker, who sings a song and banters with Jack. Jack is insulted when the gigantic Walker snubs Jack's suggestion that he play Clint's brother in a movie. But Jack auditions for the part anyway.
After Don does a man on the street interview that ends badly, Jack brings out Johnny Carson then into his first year as "Tonight" host. Carson displays samples of his various talents, including singing, drum playing and card tricks. He then does an interview with Jack where private thoughts can be heard "Strange Interlude"-style.
Ed Sullivan is nervous about doing "His first Dramatic part" on the show, but he gets into the spirit playing an attorney defending a French girl accused of murder. The case seems to be stacked against district attorney Jack when the entire jury are beret-and-smock wearing,baguette-wielding Frenchmen.
Hawaiians are thrilled to sing Aloha to stingy Jack Benny, who gets only 1 lei, while a fellow passenger is covered with them. The romantic atmosphere of the Pacific cruise back to L.A. overwhelms Jack, who envisions a zoftig blonde passenger as Jayne Mansfield. Jayne breathes "You're Just Too Marvelous," to love-struck Jack.
Jack and his long-time best friend George Burns play golf, but Jack quickly storms back to his office, crying foul to his secretary. George strolls in next, smoking a victory cigar, causing Jack to flee again. So, George makes himself at home at Jack's desk, and relates to Jack's secretary Ms. Gordon, how he met Jack 40 years before, in a cheap Chicago rooming house.
Jack Benny's guests, the folk group Peter, Paul & Mary, illustrate how folk songs develop with a tune about Jack, whose lyrics include "A silver dollar was his teething ring." Jack insists that the group cancel their flight out of town to come to his house, to discuss an important matter, at length.
Jack intros guest Nat 'King' Cole as the best friend a song ever had, in Nat's final TV performance before his death. Nat banters with Jack, plus croons "When I Fall in Love" and "Day In, Day Out." Nat reluctantly consents to sit in on piano for Jack on "Sweet Sue." At their rehearsal Jack's sax player injures his drummer's arm in a fight, so always-cool Nat calls in a 5 year old (James Bradley Jr., later played with Anita Baker and Chuck Mangione) on the skins.
Dennis Day's lugging his own scenery on stage for his song, leads an irate Jack to relate how he picked Dennis to be his show's singer, passing over an agent's offers of Sinatra (too skinny) and Bing Crosby (too bu-bu-ba-boo). Jack tracks the unknown Irish tenor from a fish market and ice cream store (Dennis is fired from both), to a Chinese restaurant.
In desperation, a psychiatrist phones Jack for his help with a distraught patient. An amnesiac with a violin has been found on the street, and he's bitterly muttering Jack's name - over and over. Jack identifies him as his long-time, long-suffering violin teacher, Professor LeBlanc, who reveals he couldn't lose his hearing, so he lost his mind.
While doing a PSA promoting safe driving, it's discovered that Jack's license expired, so the organization the PSA is for stalks out. Jack's attempt to renew his license at the Kafkaesque motor vehicle office is nightmarish.
Jack's guests, the pop singing group The Lettermen, provoke surprisingly strong reactions from Jack Benny and his regular singer Dennis Day. They bump Dennis from singing on the show at all, so he skulks behind the scenery as the Phantom of the Comedy. Jack, The Waukegan Wizard, claims he earned a high school letter as a cheerleader, but regrets he didn't attend college, so the World's Oldest Freshman enrolls with The Lettermen.
Jack demands a post-show meeting with cast and crew, furious over their mistakes. But they call him out for flubbing a line and scratching himself throughout the program. For his rash, Jack seeks treatment from a sarcastic allergy doctor with bizarre show business patients, but the doctor refers him to a highly alternative medical practitioner.
An important sponsor will soon be coming to visit, and it's up to Jack to supply a date for his daughter. He turns to Don to let his son take her out, but Harlow's never had a date before so they get a young lady teach to him how to behave with girls.
Jack Benny enlists his long-time radio and TV cast members Charlie Cantor and Mel Blanc, to playfully demonstrate how radio programs created suspense and atmosphere. Includes a parody of "The Whistler" with Jack as the diabolical Fiddler, who spins the tale of oblivious husband Griffith Park (Dennis Day), targeted for murder by his wife and her lover.