Quote 1
MR. KRALER: This isn't the black market, Mrs. Frank. This is what we call the white market… helping all of the hundreds and hundreds who are hiding out in Amsterdam. (1.2)
Mr. Kraler helps the Annex residents, even though he is risking his own life in doing so.
Quote 2
MR. KRALER: I know it's a terrible thing to ask of you, living as you are, but would you take him in with you? (1.3)
Mr. Kraler asks Mr. Frank to take in Mr. Dussel. It's a lot to ask, to add one more person to the Annex, but turning him out would mean he could die.
Quote 3
MR. KRALER: But the children…?
MR. FRANK: What they'd imagine would be worse than any reality. (2.1)
Mr. Frank isn't down with keeping the truth from the kiddos. He feels they have a right to know. The truth is less strange than fiction in his opinion.