When eight-year-old Emily Elizabeth (Darby Camp) meets an animal wizard (John Cleese) who gives her a small, ginger puppy, the girl does not expect that she will wake up and find a giant, three-meter-tall dog in her small apartment in New York. While her single mom (Sienna Guillory) is away on business, Emily and her playful but impulsive uncle Casey (Jack Whitehall) will have to deal with their new tenant.