After Gnasher's ongoing feud with the postman stops Walter from getting his weekly subscription to Magnet Monthly, he makes a complaint to the postal service. The next time Gnasher goes to 'welcome' the postman, he's met with a large robotic vehicle with iron-strong tentacles - the Post-A-Tron. Gnasher is horrified - he's one gnash away from the world record for the largest collection of samples from Post Office-issue underpants! Dennis and co menace up their own robot to take down the Post-A-Tron and restore disorder to the post-boxes of Beanotown - but it'll take a plan of some magnitude to get the job done.