Ten-year old Emil Tischbein travels by bus from Neustadt to Berlin, carrying an envelope containing 400 marks that his mother has entrusted him to deliver to his grandmother.

Emil enlists the help of a group of child "detectives" led by the street urchin Gustav, and together they track down Grundeis and overhear him plotting with The Baron and his accomplice Müller to rob a large Berlin bank by tunneling to its vault.

Eugene Archer of The New York Times wrote that "Walt Disney has come up with one of his best children's pictures", stating that Tewksbury's direction "makes all the difference.

He has kept the kiddies from gushing too coyly, suppressed the mugging of a comic trio of thieves, photographed the fresh Berlin setting in effective color, and juxtaposed suspense and wit with a nice, bouncing pace.

[4] Philip K. Scheuer of the Los Angeles Times wrote that the film "falls somewhere between the moppet trade and not-too-discriminating adults".