Mr De Testa has installed the Confiscat-inator - a state of the art security system for contraband confiscated in class - password encoded and set to be locked tight until 2050! Dennis decides there's only one thing for it - they're going to have to bust open the vault. He knows just the menaces for the job... but someone has to crack the complicated mathematical code - and the only man for the job is Walter. If Dennis can get him to join the gang, then Beanotown school is about to witness the biggest heist it's ever seen.