Gertrude Chandler Warner

Jessie wants her science fair project to make a difference. So when she gets the chance to test a local creek for pollution, she can't wait to get started. But when things start going wrong with her experiment, Jessie and her siblings don't just have an experiment to investigate, they have a mystery to solve!

When the Aldens have the chance to work at a candy factory, they try to find out who is sabotaging the candy and why.