When Ben is given a pet hamster, he's underwhelmed: until the hamster (which he has already unfortunately named 'Stinky') turns out to be a genius - a genius who helps him with his homework.

Ben's sudden improvement at school attracts the suspicion of his family - and the attention of his teacher, the horrible Beardy McCreedy. When Ben smuggles Stinky into school one day, for help with a test, the results are disastrous. But when Ben's house is burgled, Stinky can identify the culprits. And together, one boy and his hamster make a plan to trap the criminals and save the day.