The answer to this puzzle is a hint for The strange story of Lord Lefthide.
Several horsemen came across a German man. "Have you seen some twins?", they asked him.
The man answered by the negative, then added: "May I know why you're looking for them?"
"We call them the Scorpion Brothers, they have stolen something quite unique a week ago, while the guards were busy playing dice.", they answered.
"What did they steal?"
"That which is missing, of course!"
What was stolen?