Dr Ambrose Penn, the absent-minded scientist was talking to himself, and behind the skirting board the mice were listening. Monty, Mandy, Maria and Maisie were not usually interested in the Professor's scientific ideas, but this was different. This was almost unbelievable. But hadn't they heard it from Dr Ambrose Penn himself? The moon was cheese! Soon the family of mice were eagerly making preparations for the first mouse expedition to the moon. Every night when the moon came out they would think of the cheese, just hanging there in the sky, ready for the taking. One way or another the cheese mice were going to the moon.