It's Fashion Week in New York and Ellie's in charge of the dogs' modeling outfits that match their mommy-mdoels for a fashion competition. But before the first round closes, one of the designers drops dead of anaphylactic shock, her Epipen useless because someone's emptied it.

The victim's peanut allergy was well-known, so Ellie and her dog Rudy must comb through the brash designer's rivals, colleagues, and many enemies to discover who was so desperate that she committed the ultimate crime of fashion.