The August bank holiday coincides with a heatwave and in the old carriage kitchen, Sammie swelters with 100 meals to prepare and serve, while on the loco footplates the boiler kicks out an extra 1,000 degrees of heat. A trackside wall collapse threatens to stop the railway in its tracks, though a curious group of volunteers called the Wombles comes to the rescue, working through the night to get it fixed. Elsewhere, Piglet comes up with a money-spinner by sending one of the locos, little Engine 29, to another railway.