The boulder begins it's rampage running straight past a station where Gordon is waiting before smashing through bridges, signal boxes and a line of trucks near Douglas. It ploughs towards a village where the Fat Controller had just finished a pork rib before being stopped by a large rock. However it causes a crack in the rock resulting in the Fat Controller bringing in Thumper to shift it onto the rock. This fails and the boulder instead charges back on the railway. Percy, who was doing repairs on the viaduct, is then chased by the boulder through Toryreck but manages to escape on Gordon's Hill.
The boulder then rolls back to Toryreck before being diverted into a field. Harold then drops a bomb on the boulder destroying it completely. Edward, the Fat Controller and the Thin Controller survey the remains of the boulder, pondering over the cause before Edward is ordered to take away the remains of boulder in trucks to be preserved in a museum. Rusty and the remaining Narrow Gauge Engines have mixed thoughts about the incident yet while agreeing that it had to be destroyed, Rusty returns to the old line imagining that the boulder's spirit still lives on, gazing into the stars.
In the post credit scene, Diesel 10 goes to the scrapyard, only to find somebody he refers as "Master", possibly leading into Tarnished Legacy.
- Sir Topham Hatt IV
- Peregrine Percival
- Diesel 10 (appears post credits)
- Henry (cameo)
- Diesel 10’s master (mentioned)
- Crovan's Gate
- Kirk Ronan Junction
- Henry's Forest
- The Viaduct
- Gordon's Hill
- Boulder's Ledge
- Unlike all the other episodes, this episode does not have an official main character.
- The song "Back in Black" by ACDC plays when Thumper first appears.
- Footage from the previous episode is used at the beginning.
- This episode was originally named "Boulder Rides Again" as revealed in T1E2H3's TEOS Behind the Scenes.