Harry stood there, gazing at the miraculous map. He watched the tiny ink Mrs. Norris turn left and pause to sniff at something on the floor. If Filch really didn't know¡he wouldn't have to pass the Dementors at all¡.
Harry remembered what Mr. Weasley had told Mrs. Wealsey. ¡®The guards say he's been talking in his sleep¡ always the same words¡ ¡®He's at Hogwarts.'¡¯
¡°Harry, there's something I don't understand¡. Why didn't the Dementors get Sirius? I remember them coming, and then I think I passed out¡ there were so many of them¡.¡±