Because of the huge amount of damage caused by Semir & Ben, the Bundesrechnungshof (Federal Court of Auditors) sends auditor Ludwig Tietze to evaluate the situation. Tietze, who is a typical nitpicker, gets very angry when they destroy a construction site during a car chase with a gang of robbers. Unknown to him, the gang's leader is his lodger Bob Senser. When the gang strikes again, Tietze identifies Senser, and his soon taken hostage by him. In order to safe his life, Tietze tells Senser about his workplace, where large sums of money are stored inside a vault. Ben and Semir have to find them, in order to safe Tietze.
