How does Sam avoid being seen while waiting for a reply to his ransom note?
Sam hides himself by climbing up the tree he has designated as the place to leave the reply to his ransom note. In this way, he is under cover while he can see all around him because there are large, open fields in every direction.
Having mailed the note at the post office store in Poplar Grove, Sam returns to the camp and finds it empty. He risks calling out, but there is no reply. He surmises that Bill must still be playing the horse that the red-headed Black Scout is riding to the stockade. In about a half an hour, Sam hears the bushes move and a bedraggled Bill appears. He tells Sam what an ordeal he has been through; in desperation he apologizes, confessing that he just turned Black Scout out on his own, telling him to go home. However, the boy reappears at the camp in a short time. Sam consoles Bill by telling him they should get the money by midnight and be off by then. So, he goes down the hill to wait.
At half-past eight I was up in that tree as well hidden as a tree toad, waiting for the messenger to arrive. Exactly on time, a half-grown boy rides up the road on a bicycle, locates the pasteboard box at the foot of the fence post slips a folded piece of paper into it, and pedals away again back toward Summit.
Sam waits an hour and then feels it is safe for him to descend the tree. He grabs the message left by the boy and hurries back to camp. There, by the light of a lantern, he reads the message from Mr. Dorset. It is not what they have expected as there is no money inside. Instead they are told that Mr. Dorset will take his son back if Bill and Sam pay him. In despair, they agree to Mr. Dorset's terms.