Meet Billy - a timid little mouse who just knows there's a big, scary monster following him about...A big old house can be a frightening place when you're only a small mouse. And whilst big brother Bo fearlessly searches the rooms for their supper, little brother Billy can't help feeling something is lying in wait. 'Don't be so STUPID!' cries Bo in frustration after the fourth false alarm. But is Billy really being silly? Or is Bo in for a BIG surprise?