Bob is refurbishing the bandstand in the park for a concert which Farmer Pickles will conduct. Roley is excited about meeting the band, and the machines provide their own 'Oom-pah' accompaniment as they work. Farmer Pickles is driving into town to make copies of the sheet music, but it falls off the back of Travis's trailer. Spud finds the box and decides to use the music to make paper planes. As the bandstand takes shape, the machines' pistons hiss with the same rhythm as their 'Oom-pah' music. Unable to find his music, Farmer Pickles rings the band to cancel the concert. To console him, Spud gives him a paper plane - which he recognises instantly. Spud has to apologise to everyone for the trouble he's caused, when Mr. Bentley arrives for the dress rehearsal. Bob saves the day by introducing a new band - the Machines - who use their natural sounds to play a tune.