A dance floor in a field? What are we building this for, wonders Muck. Bob explains: it’s for the big line dancing competition that evening. What's more, he's got to get back home for a last-minute practice, as he is entering the contest with his dance partner Mavis Trestle.  But back at the Yard, Bob gets some bad news - Mavis has sprained her ankle! It looks as though Bob will have to pull out - until Wendy suggests that she might stand in for Mavis. Whilst Bob and Wendy are dancing the night away, back at the yard the machines, with the help of Pilchard, decide to have their own line dancing session. Of course Buffalo Bob and Western Wendy return home the triumphant winners. Yeehah!