On a train journey to Berlin, the bright young Emil from Neustadt an der Dosse meets a shady character. The man calls himself Grundeis and gives Emil a piece of candy, which makes the boy drowsy. When he wakes up at his destination, the man is gone - and so is Emil's money. He catches sight of the rogue disappearing into the city melee. There Emil meets "Gustav mit der Hupe," who detects a whiff of big adventure and when they find Grundeis, he alerts his gang. Together Emil and the Detectives embark on a chase which takes them across Berlin. Emil's little cousin Pony Hütchen emerges as one of the main protagonists in the adventure, which eventually sees the gang catching the villain red-handed. He gets convicted and the gang receives a generous reward after it turns out Grundeis is far more than a petty thief: he's a wanted bank robber.