Tests with Commissioner Klackner

But yes! I could test it with my friend Karl! Walter thought.

Karl Knackler was a police detective with the police in Walter's city. Walter had often helped him with his inventions in the past.

Knackler had a daughter named Gabriella, who solved with her friends Tom, Karsten and Kurt again and again criminal cases!

Finally, it soon rang at Walter's door. "Walter?".

"Come in, I'm in the basement!" he replied.

Quickly Mr. Knackler went to the cellar ...

And he was not astonished, because there he found ...