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“It's a mystery. I love a mystery! Imagine us as special agents!”

The Case of the Puzzling Parts is the twenty-third episode of the twenty-second series.


Sidney has a flatbed with some parts that are needed, but he forgets why the parts are needed. Paxton decides that he and Sidney should be special agents to find out what they are for, they found out from Thomas that the parts are for a diesel engine. While they are searching for more clues to find, Sidney starts to have a few problems with himself and after Paxton points out that he has a wonky horn, a broken lamp, a faulty buffer and coughing up black smoke, both diesels realise that the parts are for Sidney himself.



Voice Cast

UK and AUS


  • Joseph May as Thomas
  • William Hope as Whiff
  • Keith Wickham as Skarloey
  • Steven Kynman as Paxton and Dart
  • Bob Golding as Sidney
  • Tim Whitnall as Reg


  • Going by production order, this is the twenty-fourth episode of the twenty-second series.
  • Paxton breaks the fourth wall once again in this episode, as does Sidney.
  • This episode marks the last and only of a few things:
    • The last time Skarloey is seen without the brass ring around his funnel.
    • Whiff, Scruff, Dart and Luke's only appearances in the twenty-second series as well as Sidney and Skarloey's only speaking roles in the twenty-second series.
    • Whiff and Scruff's last appearances.
    • The last appearance of Whiff's Waste Dump, although it was mentioned in the next series.


  • When Thomas backs away from Sidney, he makes no puffing sounds and Paxton's engine does not make a sound when he reverses alongside Sidney.
  • Throughout the episode, Sidney's wheels move slower than the speed he is travelling at.
  • Nick Jr's captions misspell Sidney as Sydney throughout the episode.

In Other Languages

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Language Title
Brazilian Portuguese O Caso das Peças Intrigantes
Czech Případ tajemných součástek
Danish Sagen om de mystiske dele
Dutch De Zaak van de Onbekende Onderdelen
Finnish Varoosien arvoitus
German Auf Spurensuche
Hebrew תעלומת החלפים המסתוריים
Hungarian A fura részek ügye
Japanese ぶひんのなぞをさぐれ!
Korean 수수께끼 부품의 주인은 누구?
Norwegian Saken om de savnede delene
Polish Sprawa Tajemniczych Części
Portuguese O caso das peças misteriosas
Russian Загадочное дело
Spanish El Caso de las Piezas Misteriosas (LATAM)
El Caso de las Piezas Desconcertantes (SPN)
Swedish Mysteriet med de förbryllande delarna
Turkish Gizemli Parçalar Vakası

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