I will go with those chapters rather than the provided pages, as the pages of my edition do not line up with those chapters.
Chapter 16 begins with Isabel realizing that there is no way out for her and Ruth. She is going to have to make it happen herself, and she figures that the information she has about Lockton planning to assassinate George Washington is credible enough information to earn her freedom. The chapter starts out with a solid quote that creates suspense. Isabel is comforted by the fact that Ruth's injuries will go away; however, "Madam's threats would not."
Isabel decides that she is going to steal the list of conspirators, but she has to do this at night and not wake anybody up. The moment itself is quite tense, and readers get a good quote about Isabel's tension.
I held my breath as I lifted the lid, put my hand inside, and slowly pulled out the keys.
Unfortunately, the list isn't immediately visible to Isabel, and Isabel is momentarily at a loss.
What had he done with the list? Was it in his coat pocket? ... Had he given it to Goldbuttons for safekeeping?
The repetition of questions is important, because the unknown always serves as an effective way to build suspense and tension within characters and readers alike.
Chapter 17 has a really good quote just before a line break in the chapter. Mr. Goldbuttons has arrived at the Lockton household, and he is upset. You could use a quote that describes his demeanor or looks. He demands to talk to Lockton and storms upstairs. Lockton gives an angry roar a moment later, and readers are given a very suspenseful quote.
The plot to kill Washington had been uncovered.