Summertime has arrived on Sodor. There are more passengers arriving but less engines to do the work. Thomas calls this a "double decker" problem, which gives the Fat Controller an idea. He goes to see Bulgy (who has been a henhouse for several years) in his field to tell him that he'll be back on the road, helping to deliver passengers. Bulgy is delighted, but when he is cleaned and mended, the hens miss their old home and they creep aboard him one night, where they cause confusion and delay the next morning...