The flower show fiasco

"Because Nancy took care of her neighbor Mimsy Bourret's prize roses while she was in Paris, all three girls will be her VIP guests for the annual River Heights Flower Show. They can't wait for beautiful flowers, a fancy ballroom, and more desserts than they can imagine! But once the girls get to the show, disaster strikes. Mimsy Bourret's prize roses have vanished! Can the Clue Crew find the missing flowers in time?"--From publisher's web site.