Things start going badly in the unnamed country of this story when the old king falls ill and refuses to chose between his sons when it comes to the succession. Since Frick and Frak hate each other it is clear that King Zod's solution - to divide the kingdom in half - is not likely to work out.
In fact, the boys take it all quite literally and, in a short time, have erected a wall which makes the division a physical reality. Like many another wall it divides things rather foolishly, cutting through houses, schools, church yards and families.
In their desire to see their relatives again, one family devises a solution. First they use balloons to send messages over the wall. Then they realize that a big enough balloon will take them over the all as well.
The story tells how they build this balloon and what happens when they finally use it.
The story is based on a real event which took place in 1979, when two East German families created a four story tall balloon and managed to use it to cross the Berlin Wall, which had been erected, almost overnight, in 1961.
This is a clever little book which makes good use of the real events to tell an interesting tale. My only quibble would be with the last page, which reveals the story behind the story. It should have been set in a different typeface so that it would be clear where the story ends and the author's note begins. I found it a bit jarring to jump from the story to the history that quickly.