Sam and Julia are at school. In class they decide to go and visit with Grandpa Sailor in the mouse harbour that afternoon. They walk down the stairs, take a right at the bookshop, cross the bridge, walk out the alley and there it is: the mouse harbour. Warehouses, bridges, boats and cranes - there is so much to see here. Will you join Sam and Julia at the fishmongers, the wharf, the harbour master's office and the sailor's bar?