Marshall and his family are welcomed to their new home town by Betty Wilson who encourages Marshall's mom to buy ForeverWare - a special type of plastic container guaranteed to keep anything fresh forever. And when they say it keeps anything fresh they really do mean anything, including Mrs Wilson's twin sons who have been sealed in giant ForeverWare boxes every night for 30 years to prevent them from aging! It's up to Marshall and Simon to help the twins finally get out of the 7th grade.
—Phil G