I hate to admit it but I had to give up on this book. With climax after climax after climax, the story started to feel repetitive and tired. Christopher sneaks into the woods again and again. Christopher narrowly escapes the hissing lady over and over. Christopher and the few “good guy” grown-ups decode yet another clue from David. Christopher races against the clock and makes it just in the nick of time (must get back to the tree house before dark, must get to the hissing lady while it’s still daylight - only 10 minutes left! Must kill the hissing lady before midnight - only - 10 seconds left!)
I found myself starting to skim the pages instead of actually reading them at about the 500 page mark. Eventually I even got bored with skimming and had to concede defeat.