Bill Davis and his proper English butler, Mr. French, enjoy a carefree life in a posh Manhattan bachelor pad until Bill becomes the reluctant guardian of his brother's orphaned children. 6-year-old twins Buffy and Jody arrive at the apartment – and waste no time getting into trouble. To the dismay of shell-shocked Uncle Bill and French, teenager Sissy soon follows.

Uncle Bill decides that Buffy and Jody should be home-schooled by Mr. French when they don't quite fit in at the elite private school where he's enrolled them. Meanwhile, Sissy is surprised when the savvy and intimidating girl from her performing arts high school is also her neighbor in the apartment building.

When French accidentally knocks Buffy's beloved doll Mrs. Beasley off the terrace balcony, he goes to great lengths to find her or a replacement before Buffy discovers her loss. Meanwhile, Uncle Bill shows his warmth by offering Buffy his own childhood teddy bear.

Uncle Bill agrees to let Sissy attend her friend Sutton's party until Mr. French discovers to his horror that it's an underwear-only get-together. Meanwhile, Jody and Buffy welcome the arrival of a new bunk bed complete with bells and whistles.

Uncle Bill enrolls Sissy in his social club's manners and etiquette program for young ladies, but when she rebels against the boring class, Mr. French takes over as her etiquette tutor so that Bill won't be disappointed in his niece.

When Sissy lands the lead role in her school's play, she's disappointed to learn that her uncle's persuasion may have had something to do with it. Mr. French intercedes when Sissy declares that she's dropping out of the performance.

As Halloween nears, Uncle Bill and Mr. French plan a special trick-or-treat expedition when they realize that Halloween in New York City doesn't compare to the small-town holiday Buffy and Jody are used to. Meanwhile, Sutton tries to coerce Sissy into playing a Halloween prank on the building's superintendent.

When Uncle Bill goes on a business trip, Mr. French is asked to be the room parent in Buffy and Jody's classroom, where he learns a valuable lesson about honesty.

Sissy's romantic imagination gets the best of her when she follows Mr. French on his afternoon off and observes a liaison between him and a mysterious woman.

When Uncle Bill's plans for a perfect Christmas are thrown into disarray after the kids come down with the flu, he enlists the help of his friend to play Santa Claus to surprise the twins. Meanwhile, Mr. French meets an extremely chatty traveler while waiting for his flight to England.

When Uncle Bill forbids Sissy from going on her first date alone with one of her classmates, she devises a plan to get what she wants. Sissy learns a lesson though when her date doesn't go as smoothly as intended.

When Sissy illegally jumps the turnstile at the subway station with her friends, she is reprimanded by an officer and her Uncle Bill. Meanwhile, Mr. French helps the twins Buffy and Jody prepare for their school pageant.

When Mr. French discovers a secret about the boy Sissy has a crush on, he and Uncle Bill must decide how to break the bad news to her. Meanwhile, the twins Buffy and Jody go on an online shopping spree.