Book 23 is the next to last book of Homer's Odyssey. In Book 22, Odysseus kills Penelope's suitors and in Book 23 Eurycleia, Penelope's maidservant, awakens Penelope, who has been sound asleep while more than 100 men were slaughtered in her house.
Eurycleia's role in this book is to serve as a messenger. She awakens her mistress and tells her about what has happened. She tells Penelope about Odysseus' triumph over the suitors, but Penelope is skeptical.
Penelope controls much of the action throughout the rest of this book as she is re-united with her husband. Not only is Penelope skeptical about Eurycleia's news at first, but she is also unsure about whether the man who stands before her, after an absence of twenty years, is really her husband.
Penelope, however, tricks Odysseus into revealing the secret of how their bed was constructed, which proved to Penelope that Odysseus had, in fact, returned home:
"Now you have told me the true secret of our marriage bed, that no other mortal knew but you and I and a single maidservant" (A.S. Kline translation).
Thus, for these reasons, we may justifiably call Odyssey 23 "Penelope's Book."
Penelope has been an active agent of the narrative throughout the entire epic. In this book, she and Odysseus are finally reunited after twenty years. Up until now, even though she was what he had missed the most, Odysseus had been concentrating on other things. He met his old friends, his son (for the first time since he was a baby), and fought the suitors.
Now, he can finally be with Penelope. And she reacts to the situation in a way that is very characteristic of her! She is wary and circumspect, and comes up with a clever ruse to prove that this disguised stranger really is her long-lost husband.