Toby's Tightrope

Toby's Tightrope is a season 3 episode. Mavis gets into trouble for going on Toby's line, and is confined to shunting freight cars in the quarry, much to her disappointment. She schemes a plan to run on his line, by getting the cars to push her along the line. But when the train is ready Mavis is elsewhere, so Toby takes them instead. The cars push Toby down the line, and cause him to roll onto a collapsing bridge over a raging torrent. Toby is scared, but Mavis rushes to the rescue. After Toby is safe she apologises, and Sir Topham Hatt lets her run on Toby's line occasionally.