Stink may be a super science freak, but even Dr. Stinkelstein is feeling freaked out about having a slime mold living and growing in his very own room. At Saturday Science Club, Stink learns that these one-celled organisms are smart enough to find their way out of mazes and gang up on food sources.

When his new best friend, Ben, decides to run for class president, fourth-grade science whiz Phineas MacGuire reluctantly agrees to be his campaign manager in exchange for help with his latest experiment--cultivating exhibits for a mold museum.