I don’t really do the picking favourites thing. No favourite authors, no favourite movies, no favourite TV shows. Mostly it’s because there are so many I love that I find it difficult, if not impossible, to pick. But after some careful consideration (and a recent re-listen of the audiobook), I think I can say I have a favourite entry in the Harry Potter series. Apparently we’re all supposed to be caught up in Pottermania, so I thought I’d jump in–late to the party as always.

My favourite book is…Harry Potter And The Prisoner of Azkaban.

Why? Let me give you the extended, spoiler-filled answer. And I mean spoiler-filled for the entire series. If you haven’t read it yet, stop now and come back when you’ve finished. (And welcome to the planet Earth, I hope you enjoy your stay.)

My decision is influenced partly by hindsight and partly by the memory of when I first read it. I only got into things after The Goblet of Fire had been published and the first film released, so I was already playing catch up. I read the first two books, which were cool and kept me interested. But with the third book…the series became unputdownable. I vividly remember blitzing through the last third or so, that grand time-travelling finale that wraps up the plot. It was The Prisoner of Azkaban that got me hooked. The reasons why have only become clear now, after many re-reads and examinations. This where the hindsight comes in.

First of all, it’s in The Prisoner of Azkaban that Harry’s universe expands quite drastically. Critical pieces of the backstory and essential characters are introduced for the first time. The story is packed with revelations of all shapes and kinds. Certainly there is more to come, but an awful lot of key stuff comes into play here. Sirius Black and Remus Lupin; the Marauder’s Map and Peter Pettigrew; Dementors and the Patronus Charm. All of these things are not only introduced, they also become fixtures of the fictional universe and the ongoing arc.

We also get to explore a wider range of magical territory. The first two books were largely confined to Hogwarts Castle and its grounds. But now the third years are given the chance to visit the village of Hogsmeade. Harry also spends time away from the Dursleys before heading off to school, staying at the Leaky Cauldron for the last two weeks of summer vacation and spending a great deal of time in Diagon Alley. Both of these occasions provide a first glimpse into wizarding life and personalities outside of school. We’re getting outside a bit more and it’s a breath of fresh air.

The second reason this is my favourite is also getting a bit cliche: the story is “darker” and “grittier” than the first two books. While there was plenty of villainy and danger before, in this one the threat becomes far more personal than even the bullyings of Malfoy and the Slytherins. While Voldemort has faced off with Harry already, in both cases it was largely contained in the final climax. Here there is someone out there who is specifically “trying to kill” him (Sirius isn’t, of course, but we believe he is for most of the page count). Not only is he singled out by his extreme reaction to the Dementors, he is constantly bombarded with predictions of doom and death by Professor Trelawney–and he begins to half believe them. None of this is the darkest the series will get, but think of it as another way this book expands the world. This is just a taste of the intensity that is to come.

But darkness isn’t the only thing to come to the fore. Harry himself overcomes his challenges admirably and truly begins his long journey to maturity. There are a fair share of personal victories for him in this story, not the least of which is his newfound ability to conjure a Patronus, which we’re told is a very advanced piece of magic. And in one of the brightest moments, he bounces back from a terrible defeat on the pitch to finally capture the Quidditch Cup for Gryffindor single-handedly. His growing maturity is pointed out when Professor Lupin hears that Harry’s greatest fear is not Lord Voldemort but the Dementors. He comments, “That suggests that what you fear the most is fear itself. Very wise, Harry.”

Wisdom isn’t automatically granted to Harry, though. He is still young and impulsive, and he sometimes displays a greater degree of foolishness than he did before. His drive to rush into danger (what Hermione later calls his “saving people thing”) served him well during his first two years, but here it almost leads to disaster at the climax. He takes greater risks with the invisibility cloak, using it in Hogsmeade among crowds of people. And most tellingly, when he discovers someone is trying to kill him he tends to think little or nothing of his personal safety–even succumbing to the immature desire for revenge and hatred against Sirius Black. Some might call it bravery, but it really resembles nothing so much as thirteen-year-old impulsiveness.

Finally, there is one more reason why I find Harry Potter And The Prisoner of Azkaban such an amazing book. It has to do entirely with plot and the narrative arc of the entire series. This third entry contains one of those beautiful pieces of misdirection that are so essential to mysteries and long narrative arcs. It has to do with the death of Harry’s parents and the reason Voldemort tried to kill him when he was a baby.

Remember the end of the first book? Harry asks Dumbledore the very thing the reader has been asking the whole time: “Why did Voldemort kill my parents?” Dumbledore gives no answer. The question is left dangling in front of us, a mystery we know we will have to wait to see unravelled.

TV shows which have ongoing arcs face the challenge of creating a sense of intrigue while also moving the story forward. The one comes with mystery and unanswered questions…and the second means answering the questions and solving the mystery, thus losing the intrigue. Some writers choose to drag things out to the bitter end. Others figure out ways of answering a question while raising three more.

J.K. Rowling…well…she makes us think she’s answered the question, when really she hasn’t.

In The Prisoner of Azkaban, we learn that James and Lily Potter were somehow involved in a resistance movement against Voldemort. Hence he tried to kill them, they went into hiding, Pettigrew betrayed them, etc. This sounds perfectly reasonable and rather complete. But what we have no reason to suspect is that vital information is being held back. And it must be held back. The revelation of the prophecy in The Order of The Phoenix acts as a catalyst both emotionally and narratively for the last two books (a full analysis of that would take too long; just trust me on this point). It’s impossible to bring it in earlier. So our beloved author finds a way to placate us while she saves the big stunner for when it will have the most impact.

It may not seem like much, but the authorial decision to partially answer a lingering question while still holding something back is hard to accomplish. Once again Rowling proves that she is a born mystery writer capable of spinning a yarn into wool and getting us to willingly pull it over our own eyes.

That about sums it up for me. I could go on and on about why this one is my favourite, especially dealing with the finale, but I’ve taken up far too much of your time as it is. So let me ask you the question in return: What’s your favourite Harry Potter book? And while I don’t expect you to be as verbose as I was, I am going to ask that you be able to tell me why.