Only you can answer this question. I can tell you which part I think is most exciting, but to you it might be another scene. Any time the Franks think they have been discovered, the tension builds and the scene becomes more exciting in that sense to me.
I've pasted below a link to a web site where you can find good advice on how to interpret a piece of literature. Read over that and see if it helps you. You might even consider renting a movie version of the play. Keep your copy of the play and a notebook beside you as you watch so that you can jot down notes while you watch.
The most important thing about a question like this one is that the answer must come from you.
This question is for you to find out by reading her diary and try to sum up the most exciting parts that YOU think is good :)