A crime has occurred in room 4B! A classmate has had a priceless and precious toy stolen: the Scarlet Tamagotchi. So Iñaki and his turtle friend Cecilio transform themselves into 1940s private detectives to solve the mystery. However, they will have to face dark forces that will not make their task easy.
| Actor | Role |
|---|---|
| MMaria Ignacia HargreavesIñaki | Iñaki |
| LLucas EngelCecilio | Cecilio |
 Paco PasquetteProfesor Fernando / Facundo / Don Cheba | Profesor Fernando / Facundo / Don Cheba |
 Consuelo CarreñoAmanda | Amanda |
| GGuillermo AriasAurelio (El niño dinosaurio) | Aurelio (El niño dinosaurio) |
| FFrancisco Visceral RiveraDani | Dani |
 Alejandra MoffatMagdalena | Magdalena |