Tim is a brand-new locomotive fresh from the workshop, featuring an innovation called roller bearings. These axles use spinning cylinders to reduce friction and wear. Sent to the yard where his Uncle Smedley works, Tim learns about Kid Friction, a menace who grinds metal against metal and causes overheated bearings called hotboxes. On his first job, Tim is stopped cold and sent to the sheds. When Kid Friction strikes again, Tim and his roller bearings are ready to stop him.
