Crates fall onto the road from a moving truck, attracting the attention of two boys. One of the crates has a butterfly painted on it, which suddenly begins to fly. The boys run after it and end up in a shed where an old locomotive is parked. The younger boy climbs aboard and drives away. The older boy sets off after him on a handcar. They meet a stationmaster who informs them that another train is about to arrive on the same track as the locomotive. To avoid a disaster, he switches the points. The train is stopped. The boys say goodbye to the stationmaster and drive off towards the shed.