It's the 1930's. American sisters Eugenia Crocker and Nesta Pett are extremely wealthy and extremely competitive, with each disliking the other. Their latest quest of oneupsmanship has Nesta trying to marry off her niece by marriage, poetess turned crime novelist Ann Chester, to Lord Reginald Wisbeach, so that there will royalty in the family. This move is against Ann's wishes as she doesn't love the stuffy Lord. Meanwhile, Eugenia, now living in London, is trying to buy a royal title. Eugenia's current quest and others like it are always hindered by the notoriety of her stepson, James Crocker - better known as Piccadilly Jim, for the newspaper gossip column he used to write and the job from which he got fired - who is known as a womanizer, brawler, gambler and drunk. Jim is thinking about becoming more respectable when he meets and falls in love at first sight with a beautiful American visiting London. That woman is Ann, who hates what she knows of Jim, not only for that notoriety, but also because Piccadilly Jim the columnist once criticized her book of love poems (although it was not actually Jim who was writing the column at the time) which she felt ruined her career. Although Jim doesn't know why Ann doesn't like "Piccadilly Jim" as she has never met him, he, in his pursuit of her which takes them back to New York, assumes the name Algernon Bayliss, who is actually the Crocker family butler. Ann, who wants a man with an adventurous streak, too falls in love with "Bayliss", despite his overwhelming respectability, although she would prefer if he was a little more dangerous. Throw into the mix cases of mistaken identity (as the Petts and Crockers have never met), a German spy, a fake maid, a secret explosive liquid, and a not so kidnapping of a whiskey-swilling, chain-smoking child, and Ann may figure out what or who she really wants in life.