Hoping to lift Arlo's spirits, Maddie, Thelma and Frank decide to finally celebrate Christmas for once. Buoyed by the sudden holiday cheer, Arlo surprises Maddie with an unwelcome gift: her estranged mother.
Kirstie revolves around Madison "Maddie" Banks, a renowned Broadway star who finds her life turned upside down when Arlo, the son she gave up at birth, suddenly appears hoping to connect after his adoptive parents have died.
However, Maddie doesn't exactly see nerdy and schlubby Arlo fitting in with her luxurious lifestyle. But when Maddie's assistant and best friend, Thelma, and outlandish driver Frank encourage her to give Arlo a chance, Maddie is shocked to find that perhaps she has motherly instincts after all.