Pictureland — Alan Cook

Matthew and Mason are intrigued by the painting on their wall, and with the help of Amy, a girl in the picture, they enter the land behind the painting. What they find there is a dystopian world far different from the idyllic picture, where people have chips in their heads and thought control is practiced. The three must attempt to destroy the people who are in control of the tyranny before they are thrown into the Bloody Tower where dissidents are imprisoned, or, in the case of the boys, executed.