Twelve year old Thomas Miller (Forrest Landis) is known for telling tall-tales. He has convinced his 6th grade class there are snakes hiding in the school toilets and that the science teacher is a government spy conducting secret tests in their classroom. But when Thomas discovers a real secret that could put his school in danger he finds the courage to tell the truth - but who will believe him? The kids at school make fun of him. Thomas has gone to the principal's office as often as he is called on in class. His mum (Lea Thompson), who is the principal's assistant, is at the end of her rope, and maybe her job, if he doesn't stop. To make matters worse, Thomas has a crush on the new girl at school, who pays more attention to the bullies than to Thomas. His only friend is Jackie, (AnnaSophia Robb) the skateboarding chick who stands by him.