Danger on the Line is a magazine story with the theme of "movement".
Thomas is sleeping on a siding when he rolls backwards and biffs the buffers. Henry sees it all and teases Thomas and accuses him of not knowing when he is moving. Later, Thomas feels the rails moving beneath him. When his driver takes a closer inspection he realises that some earth had fallen away from the embankment, which is unsafe. Thomas warns the signalman and Henry about the danger. Henry, who was very grateful, decided not to tease Thomas for a while!