Jim Crocker, a popular London-based American caricaturist known by his pen name 'Piccadilly Jim' (played by Robert Montgomery), moves through the city’s social scene with ease and a mischievous charm. He supports his father, James Crocker, Sr. (an out-of-work actor who adores Shakespeare but often forgets his lines), portrayed by Frank Morgan, whose hammy flair both amuses and embarrasses Jim. Jim’s life of wit and whim is perfectly managed by his impeccably polished valet, Bayliss (Eric Blore) — a duo that keeps the chaos of show business neatly in check.
The plot twists when Eugenia Willis, Nesta Pett’s sister and Nesta’s own sister-in-law-to-be, enters the picture. Eugenia is played by Billie Burke, and Nesta Pett (Cora Witherspoon) is Eugenia’s domineering sister who questions James Crocker, Sr.’s sincerity and financial steadiness. Nesta’s doubts cast a shadow over Jim’s happiness, and a morning confrontation after Nesta discovers Jim’s true identity as a caricaturist (not the “artist” James portrays) further strains the looming engagement. Amid these tensions, Jim’s heart turns toward Nesta’s niece, Ann Chester (Madge Evans), whom he meets in a nightclub and immediately falls for, despite Ann’s engagement to Lord Frederick “Freddie” Priory (Ralph Forbes).
Jim’s career ascends as he is fired from work for missed deadlines, yet this setback becomes fortune’s door. The Pett family accompanies Eugenia and Ann on a Riviera sojourn, and Jim channels his misfortune into a comic strip inspired by the Petts — a witty, affectionate spoof titled From Rags to Riches, featuring the “Richswitch Family.” The strip’s success is instantaneous, and Jim, newly flush with wealth, hires detectives to locate Ann, hoping to win her heart.
When the Petts return to England, their public recognition as the drawing subjects turns them into the town’s joke, much to Ann’s fury and Nesta’s chagrin. To salvage the romance, Jim adopts a bold disguise, hiding his true identity as the son of his valet Bayliss, and schemes to spend a few hours with Ann before Nesta and the family depart for the United States. Jim also crosses to New York on the same ship as Ann and Freddie, hoping to win her while dealing with the tangled fallout of his “artist” identity. Before he departs England, he attempts to cancel the comic strip, only to learn he doesn’t own the rights; to his dismay, the strip has already been picked up by American newspapers.
Despite turning Nesta’s and the Petts’ lives into something kinder through his art, Ann discovers that the “Bayliss’s son” is Piccadilly Jim, and she is torn between loyalty and love. Meanwhile, James Crocker, Sr. tries to impress Eugenia by posing as the Danish Count Olav Osric, a deception that backfires as Bayliss grows suspicious of Freddie’s claimed lineage. At a lively party, Jim declares that he will “unmask the imposter,” a moment that flusters James and leads to a dramatic revelation of true identity, resulting in his rejection by the Petts.
With pride bruised but love still possible, Jim contemplates returning to London. On the ship, Bayliss encourages him not to give up, and Jim makes a bold move: he leaps onto the lowering gangplank, colliding with Ann, who has come to realize her feelings for him. The not-so-sly caricaturist wins out over the pretenses, and the film culminates in a romantic kiss as the couple confirms their love.