In act 2, scene 1 of The Diary of Anne Frank, Mr. Kraler reveals to Mr. Frank that one of the workmen has approached him about the whereabouts of the Franks. Mr. Kraler didn't think much of it until the man asked about a door that used to go up to a loft. Immediately thereafter, the man asked for twenty guilders added to his pay each week. Mr. Kraler says the man didn't define his demand as blackmail, so he isn't sure if that is the case or not. Mr. Van Dann immediately believes it is blackmail and the man knows about Jews hiding on the premises. 

First, Mr. Frank asks Mr. Kraler what the going rate for keeping quiet about hiding Jews is. Mr. Kraler says that a war plant could offer him twenty guilders more a week, but they do not operate a war plant. Again, Kraler says that he's not sure if the workman actually knows that Jews are hiding on the premises or not. Mr. Frank, using his good business sense, tells Mr. Kraler to offer the man half, ten guilders a week, and see if he takes it. The point behind offering the workman half of what he demands may prove to Mr. Frank and Mr. Kraler if he knows anything about the Jews hiding for sure. If the workman isn't quite sure, he may settle for the ten guilders. However, if the workman is sure that Jews are hiding in the annex, then he might refuse the ten guilders more a week and demand twenty because he knows he has the controlling information on the subject. If Mr. Kraler caves easily, or acts desperately, though, that may also reassure the workman that there really are Jews hiding in the loft. Therefore, the best scenario is to do what Mr. Frank says and only offer the workman half. This dares the workman to ask for more and/or reveal what he actually knows. Then once they see how the workman reacts, they can make a more aggressive decision if needed.