If you were caught playing with your spinach -- or worse, using long, stringy bits of it to write "I hate what Mom makes me eat" -- what would happen? You'd probably get grounded for a few days, right? But imagine if you got locked up for years on end, and maybe you'll better understand Ned Mouse's predicament.
Sure, he wrote with his spinach, but it's what he wrote that got him into hot water with folks who are much less forgiving of criticism than parents are -- the government.
After he scribbles "The government is unfair to mice," Ned finds himself dressed in a convict's stripes and thrown into a cramped cell with a guard who just can't understand why anyone in prison would want to get out.