Episode 23: A Breakthrough Discovery was uploaded on November 3, 2016 and is the seventh episode of the third season.
Autumn is in full swing on the Island of Sodor, and the winds have returned, but colder than usual.
One November morning, Sir Topham Hatt has a special job for Henry. He is told to take a train of equipment up to the Aluminum Plant at Peel Godred in the afternoon and advises Henry to be careful and go easy, as there's supposed to be a storm later in the day. At that time, the sun was shining, but by late afternoon, as Henry picks up his train, the sky becomes dark with ominous gray clouds. Henry looks up at the sky and says that he thought he'd overcome his fear of the rain. Emily says she'd care more about damage to the line rather then Henry's paintwork. Henry agrees with Emily, but he pretends he didn't hear her, and Henry departs with his train.
Turns out Sir Topham Hatt was right about the storm. As Henry puffs up the line, the storm grows darker and darker. Rain also begins to fall, lightly at first. As Henry makes it to Killdane and up the Peel Godred Branch, the rain furiously begins slamming into him. When Henry arrives at the Aluminum Works, he sees a foreman standing outside. However, it is raining so hard it makes it difficult to hear what he's saying. The foreman says to leave Henry's load there and he can go up to the old depot for shelter, as there's a covered shed. As soon as Henry was uncoupled, he quickly made his way to the old depot. The shed mentioned earlier was old and worn, but Henry doesn't care, he's just glad to be out of the rain. Henry remarks that he's never been here before and that the place looks a little eerie. His driver explains that it's the Old Steel Works Transfer Yard, and there used to be a narrow gauge railway here. Henry can see the railway's line, but all that's left is one straight strip next to the transfer platform.
It soon stops raining, and Henry is ready to leave when he hears a voice, and wonders who's there. The sound is echoing, making it very spooky! Henry and his driver waste no time in leaving.
The next morning at Tidmouth Sheds, Henry explains to to the others about what he heard. James says that there was "a guy" singing Tiptoe Through the Tulips, while Gordon thinks it may have been a stoner. Henry says they think so, but his voice echoed in a way that was very disturbing; like a ghost. Thomas says "not more nonsense", Henry tells him that it wasn't a ghost, but it sounded like one. Percy points out that a lot of engines used to work there, so it could be. James disagrees with Percy saying, "STUFF AND NONSENSE!".
Later in the day, Henry and his crew tell Sir Topham Hatt about it, he finds it interesting and says he'll check it out later in the evening.
The next morning Sir Topham Hatt tells Henry that he was right about those voices, but after searching the whole area, he couldn't find anything or anyone. He suggests to Henry that whatever it was he and his crew heard was possibly hiding in the buildings. This looks like a job for Jenny's Pack!
Miss Jenny loans Jack, Alfie and Oliver and Henry takes them to the place where he heard the voice. The foreman orders Jack, Alfie and Oliver to clear some of the debris from around the area and clean up the place. The three go to work, digging up things by dirt and getting rid of many prickly bushes that had barred the entrances to some of the buildings. They even had to knock down some walls if the buildings were unsafe for the workmen to explore. However, they don't hear the voice at all. They uncover many rusty slate cars, but no engines. However, they don't notice the ground around the chimney beginning to crumble.
By evening, the site was all cleaned up, but the source of the voice wasn't found. Henry thinks that whatever it was must have left before they came. Oliver says that if it was an engine, it couldn't have gone anywhere without fire(should be water) and coal. Alfie thinks they might have accidentally crushed and killed them, but Jack reminds him that he'd know when it happened, Alfie suggests blood, Jack tells him that he'd hear them screaming. Just then, the voice comes back! Alfie says it sounds like a ghost. Oliver listens closely, and suggests that it's a vehicle. Henry's driver suggests that it's coming from the chimney. Oliver races towards it without thinking, the ground suddenly starts sinking! When the dust clears, Oliver says he's found the source: an old engine! The old engine doesn't hear Oliver and he repeats the message. The old engine, whose name is Jim, says that he'd been down there for so long, he must have been going deaf. Henry says it made sense why Jim didn't respond to them.
Jim is towed out of the hole and to the rails and looking very shabby. He says that he used to work on The Mid Sodor Railway and he was moved here after it closed in 1947. Jack asks why Jim was underground and if he was buried. Jim says he was put in the military bunker when they no longer could afford to run him. Henry says he remembers talk about the old military bunkers underground in this area, but didn't think there would be one here, but it made sense how the chimney made Jim's voice sound distorted like a ghost and the chimney was connected to the bunker. Jim asks if Stuart and Falcon are still in service, they now have new names and Duke is also in service. Jim doesn't believe Henry at first, but like him, Duke was found. Henry remarks that Jim has a lot of catching up to do.
Jim is then taken to Crovan's Gate for a overhaul and is as good as new by spring. One morning Duke waits outside the carriage shed when Peter Sam and Sir Handel come racing into the yards. The doors of the shed fling open, revealing the spotless green engine. Peter Sam and Sir Handel are gobsmacked and are happy to see their old friend.
- Sir Handel
- Peter Sam
- Oliver (excavator)
- Duke (does not speak, spoke in original script)
- Toby (cameo)
- Henrietta (cameo)
- Annie & Clarabel (cameo)
- The Sodor Garratt (cameo)
- Kevin (cameo)
- George (original script)
- Albert (mentioned)
- Crimson (mentioned)
- Lower Arlesbourgh
- Tidmouth Sheds
- The Viaduct
- Peel Godred
- The Sodor Steamworks
- Crovan's Gate
- The original plan was to upload two Halloween episodes, but T1E2H3 decided to make the second of those a special. There wasn't enough time to make another episode before Halloween so the release date was slightly pushed back.
- This marks first appearance of the Pack in The Engines of Sodor, excluding Jack's minor role in The Road Rebel with Rollers.
- George was going to appear, having Oliver's role of falling through the bunker. He was taken out during scriptwriting and replaced by Oliver (who had already been in the script) because the Pack's task did not seem like a job that would need a steamroller. Other pack members, such as Max and Monty, were not in any script.
- This is the first Engines of Sodor episode to be uploaded in November.
- Duke spoke in the original script, but T1E2H3 forgot to record his line.
- Jim sings "Tiptoe Through the Tulips" by Tiny Tim. He also references Kenneth Grahame's 1908 book "The Wind in the Willows".
- The last part of this episode takes place in the spring of 2017. The episode was made in November 2016, thus making it the first episode to have scenes in the future.
- When The Sodor Garratt appears, Cory is facing the wrong way.
- When the scene cuts to Knapford, Gordon's whistle is heard, but he is nowhere to be seen.
- Oliver says an engine can't go anywhere without fire and coal, when it should have been water and coal.