Ten-year-old Hannes, growing up with his young, single mother, wants to join the coolest gang in town, the Vorstadtkrokodile. But the initiation goes awry and his life is saved by Kai, who is desperate to join also. But Kai is wheelchair bound and unable to even run away when things get hot. When Kai witnesses a break-in, he suddenly becomes of great interest to the gang, being the only witness. He, in turn, will talk only if he can join. With his help, youthful imagination and courage, the group sets off to solve the case and take on the apparently unbeatable criminal gang.