|Trick or Treat|
|Air date||November 8, 2014|
|Full Dream Ahead||Deus Ex Machina|
One evening on a moonlit night, Henry was preparing to take a goods train to the other end of the line. While preparing to leave, Edward warns him that on moonlit nights when a fog is about, there is also a ghost. Henry, a bit put off by Edward's creepy warning, sets off in the night. In his train is S.C. Ruffey, who is currently the host of a demon, is intent on causing trouble and spooking Henry. As Henry heads along the line, a fog rolls in, and he is forced to stop a danger signal, with a notice which read "beware of the slender engine." The spirit subsequently appears, absorbing Henry and the demon within S.C. Ruffey.
During Henry's trip, Stephen visits Tidmouth Sheds, where he shares the rules of Halloween with the engines present in hopes of preventing trouble. Despite the other engines indifference, Stephen warns those gathered of the dark nature of Halloween, listing three rules which must be followed to protect themselves from the evil which lurks. The rules are as follows: 1. Always wear a costume; 2. Hand out Candy; 3. Never blow out a lit jack-o'-lantern. Subsuquently, Stephen warns of engine with pumpkin orange paint and a face concealed by a mask who roams the island on Halloween night to enforce the rules.
The next morning, the engines awake, surprised Henry has not yet returned. Assuming he spent the night elsewhere, Gordon sets off with his Vicarstown express. Halfway there, he comes along Henry's derailed train, finding the trucks to be in a sort of daze with no relocation of the prior night's events. Later that evening, Gordon is at Vicarstown preparing for his return run. Whilst Stanley is arranging his train, the pair discuss Henry's bizarre disappearance, also noting that Bill and Ben have gone missing. Stanley warns Gordon to be careful, but Gordon sets out with an air of confidence, despite his own fear. On his way, Gordon encounters the Slender Engine.
The following morning, Thomas and Percy are at Knapford Station preparing for the upcoming Halloween party. Hank arrives to report of Gordon and many other disappearances the previous night. Hank and Percy show concern for their safety, but Thomas is certain he will be unaffected in that he is the star of the show. Percy suggests consulting Stephen, but is quickly turned down by Thomas.
Much to Percy's dismay, he must pull the Mail train that night. Percy fearfully hurries along the line, where he inevitably encounters the Slender Engine, who has now absorbed the demon. Percy rushes back to Knapford, where the Slender Engine pursues him. Before the Slender Engine can affect Percy however, the jack-o'-lanterns at the station vaporize the Slender Engine, leaving Percy confused.
The following morning, Percy rushes to Tidmouth Sheds, awaking Thomas. Percy reveals his discovery of the Slender Engine to Thomas, realizing that the spirit also captured James as well. Percy and Thomas set off to assemble the rest of the engines at Knapford the that evening's Halloween party, all in costume.
That evening, all of the remaining engines are at Knapford in costume. The group reports further disappearances, and Percy deduces their disappearances are the result of the Slender Engine. Thomas disputes this, claiming the Slender Engine is only a railway legend. Percy refutes this, recounting his multiple encounters with the spirit. After mentioning the Slender Engine had glowing red eyes, Edward deduces that the Slender Engine absorbed the demon and increased its power. Despite Edward's concern, Stephen reassures everyone that as long as they remain near the jack-o'-lanterns, they will be safe.
Shortly thereafter, the ominous puffs of the Slender Engine can be heard. A strong wind gusts through the station, extinguishing the jack-o'-lanterns. The station erupts in chaos when the Slender Engine appears as the engines all attempt to escape. Thomas and Percy manage to escape, hiding in the goods shed near the yard. Percy is fearful, while Thomas is grossly unconcerned as a result of his star status. The pair soon hear the ominous approach of the Slender Engine. The specter appears, and Thomas and Percy brace for the worse. Quite miraculously, the Slender is whisked away by an unknown force. This force is revealed to be the Halloween Engine Stephen mentioned, intervening to punish the Slender Engine for blowing out jack-o'-lanterns. Thomas and Percy realize they are not in costume, and are dealt punishment by the Halloween Engine.
- Diesel 10
- Iron 'Arry
- S.C. Ruffey
- Troublesome Trucks
- Slender Engine (does not speak)
- The Halloween Engine (does not speak)
- Donald & Douglas (mentioned)
- Bill & Ben (mentioned)
- BoCo (mentioned)
- Diesel (mentioned)
- Iron Bert (mentioned)
- Murdoch (mentioned)
- Spencer (mentioned)
- Rosie (mentioned)
- Molly (metioned)
- Billy (mentioned)
- Neville (mentioned)
- Oliver (cameo)
- Stepney (cameo)
- Mavis (cameo)
- Salty (cameo)
- Dennis (cameo)
- Toad (cameo)
- During the halloween party at Knapford, all the engines are in costume. The following are their respective getups:
- Thomas: Emmett
- Edward: UniKity
- Percy: Elsa
- Hank: Lego House?
- Duck, Oliver, Stepney and Arthur: Teenage Mutant Ninja Turtles
- Emily: Scottish Flag (referencing the contemporary Scottish Independence Referendum)
- Diesel 10 & Mavis: Vampires
- Toby, Stephen, Salty, and 'Arry: Ghosts