What does Jack tell Harry about where they should go, what does Harry see when she is sleeping and what does she see in the fire when she wakes up?

Jack points out, as he and Harry talk, that Ritger's gap is very narrow and should prove to be a perfect bottleneck. In a dream that night, Harry sees the Gap, and realizes Jack is right. When she wakes, she sees Corlath's face in the fire, and is saddened by the look of sorrow on his face.