Henry is a theatre-mouse: he knows little of life beyond the walls of the Lyceum Theatre. Henry is, however, full of dreams and ambitions - to run his own circus along with all his mousey pals. One day a visitor from the outside world arrives at the theatre with an ice-cream delivery and Henry comes up with a plan to fulfil his dreams. Their adventures in the countryside outside the town begin. Have Henry and his friends bitten off more than they can chew?