Loving everything scientific except spiders, an arachnophobic Stink reluctantly attempts desensitization therapy exercises recommended by Judy and Webster before a real-life, fact-filled encounter takes them all by surprise.

After learning about slime molds during the Saturday Science Club, Stink finds the organism growing in his room and starting to take over the world.

A class visit to the Gross-Me-Out exhibit at the science museum inspires Stink Moody to create a variety of terrible smells to put on the sneakers he plans to enter in the World's Worst Super-Stinky Sneaker contest.

Stink Moody, friends Webster and Sophie, and Mrs. Birdwistle visit tourist attractions in Virginia as they try to give away 101 guinea pigs rescued from a laboratory, although Stink is very reluctant to give away his favorite, Astro.

When it is "Backward Day," Judy must turn her usual sour mood upside down and be happy and nice for a change.