Flora Whiff (Bebe Neuwirth), the famous expert on smell — whose ""nose knows"" — comes to school to judge the First Annual Smell Search. Ms. Frizzle's class creates a unique smell which is bound to take first prize, but Arnold's cousin, Janet, determined to win by herself, changes their smell to an odour only a skunk could love. The kids discover the secret to what makes things smell... now they have to make sure their creation doesn't make a big stink!