Notes From The Underground by Part 2 Chapter 7 Page 18

to a dance somewhere in a private house, a family of “very nice people, WHO KNEW NOTHING, absolutely nothing, for she had only come here so lately and it had all happened ...

and she hadn't made up her mind to stay and was certainly going away as soon as she had paid her debt...” and at that party there had been the student who had danced with her all the evening. He had talked to her, and it turned out that he had known her in old days at Riga when he was a child, they had played together, but a very long time ago--and he knew her parents, but ABOUT THIS he knew nothing, nothing whatever, and had no suspicion! And the day after the dance (three days ago) he had sent her that letter through the friend with whom she had gone to the party ... and ... well, that was all.