What's That Sound?

Series for pre-school children. Little Bo visits her uncle, Roly Mo, in Fimble Valley every day and there's always something exciting to do during a visit, especially when Yugo and Migo are close at hand. There's a strange sound in Roly's home today, but no-one can work out what it is. Meanwhile, Roly's Moly Munchies have gone missing - can they find them in time for tea?