Toby's Tightrope is the fifteenth episode ever made in Season 3.
Mavis has been confined to the quarry and complains to Percy, who is quite unsympathetic. When a thraw increases production at the quarry, Mavis uses the chance to be allowed to go further down Toby's tramway, but gets too big for her buffers and asks the trucks to push her down the line. However, when she is away, Toby comes and they push him down the line onto a bridge swept away by a landslide, leaving only rails behind. Mavis goes to the rescue and confesses it was her fault, but the Fat Controller and the manager are pleased and allow her to travel on the branchline.
- George Carlin calls the chains ropes. Michael Angelis made the same error in his first narration of this episode.