Big and Small hear a strange sound one night and, when they investigate, discover it's Ruby practicing a new song she has written about how lovely the moon is that night. Big thinks the song should be softer - and invents a Twanger to help out Ruby. Small thinks soft is, well, soft: she should have LOUD! Loud as in a trolley of ribbiting frogs. Enough! calls out Ruby as she dodges flying Twangers and over-excited amphibians. It's her song - do Big and Small really want to help her or do they really want to do their own thing? Put like that... Big and Small join with Ruby to sing her song, her way, and they agree - it's not too loud and not too soft, yup, it just sounds good. Big and Small try to write a song for Ruby - but it's not easy playing a Twanger!