Spoiler warning: Don't read this review if you haven't finished Harry Potter Book 7. Because this is very much Book 8 in plot terms, we — and the writers of the book — assume you've come that far.

According to J.K. Rowling, this is it: there will be no Book 9. The author may one day decide to go all Reichenbach Falls on that statement; still, it falls to us to consider Book 8, also known as the rehearsal script to the just-opened London play (actually a pair of plays) Harry Potter and the Cursed Child, as the absolute and final end of the published Harry Potter series.

SEE ALSO: Everything you need to know about the new Harry Potter book

Is it a worthy capstone for the Boy Who Lived, the defeater of Voldemort, the greatest wizard in Hogwarts history? Short answer: yes. Script writer Jack Thorne has got the voices of our beloved characters down, and introduced us to some believable new ones. He has done his story collaborator, one J.K. Rowling, proud.

Caveat to the longer answer: Your mileage may vary depending on your expectations — such as whether you actually knew Thorne wrote it. If you come to the book seeking Harry Potter novel number 8 — which, given the marketing hoopla and midnight book launch parties, you'd be forgiven for expecting — you may be disappointed.

There is no sumptuous Rowling prose here to link the dialogue. You are no longer handheld through Harry's adventures in prose as transporting and soothing as your mom's voice. No, this is a book to be devoured in the theater of the mind, and it requires a little more imagination on your part.

See the performance in your head as if you're sitting in the audience, and you'll have a fine old time. Better yet, grab a few friends and actually act the play out in front of a few other friends. (More than a few booksellers recommended this when the book went on sale Sunday.)

If anyone can bring back the old-time tradition of reading plays out loud in your home, it's J.K. Rowling

If there's anyone who can bring back the old-time tradition of reading plays out loud in your home as entertainment, it's J.K. Rowling and her half a billion-strong army of readers. This book is a worthy place for them to start.

Be sure to leave lots of room in your performance for laughter lines, because Cursed Child — despite being overall even more dark and Dementor-filled than its Dumbledore-killing predecessor, Harry Potter than the Deathly Hallows — is surprisingly funny.

Best out-of-context quote in #HarryPotterAndTheCursedChild: "You're upsetting the dementors." — Chris Taylor (@FutureBoy) July 31, 2016

And at the same time, like every book in the series, Book 8 succeeds in breaking new age-related emotional ground for Harry, Ron and Hermione. Here we pick up precisely where the epilogue of Book 7 left off, and find them wistful and nostalgic and loving and in desk jobs and slightly disillusioned in a way that will have fortysomethings everywhere nodding their happy, weary heads.

"In every shining moment is that drop of poison," an old and wise friend of Harry tells him. "The knowledge that pain will come again." At another moment, Ron Weasley puts it more earthily: "Honestly, every time I sit down, I make an 'oof' noise. An 'oof'."

The old characters may be literally creaky, but Cursed Child itself feels fresh. It is trying something new for the series, something risky, something that should speak in a very real way to both old and young readers — and that's a great thing for the final book in a fantasy series.

There is risk in making Albus Potter, Harry's son, and Scorpius Malfoy, son of Draco, the friends at the center of the play; it could feel too much like Hogwarts: The Next Generation. There is also risk in making their personalities the polar opposite of their fathers'; it could seem just like the obvious, cynical choice.

But in such clear opposites is drama forged, if you're a good dramatist, and some of the book's most touching moments come when Harry tries to connect with his difficult son — haltingly, fearfully, fully aware that orphan parents have no experience in such matters.

Also risky: making the Time-Turner the center of the action, at last. This handy-dandy time machine has been hovering around the edges of Harry's story since Prisoner of Azkaban, but its implications and outer limits have never been fully explored. Hermione used one to take more classes; she and Harry used one to go back a mere three hours in time and save Sirius Black.

The Harry Potter series is full of people solemnly swearing they were up to no good with this or that magical item; it was about time someone got up to no good with a Time-Turner. The risk is that some Potter fans might not like the wonderfully timey-wimey, Doctor Who-style result. But even if you are no Whovian (really?) at least it's consistent with what has been previously established about the Potter universe.

I won't say too much about the marvelous reveal at the end of Cursed Child Part One; the show is all about its slogan #KeepTheSecrets. Suffice to say that the way it is executed, it could stand as one of the better cliffhangers in any time travel tale.

The climax of Part Two? Not so great, plot-wise. But by then, we're fully, emotionally invested, so it doesn't matter. It strikes the right emotional tone, at least. The end of Harry's story is here; so in several senses are the beginning.

Again, your mileage may vary. But for me, I don't think there's ever been a better end to an eight-book ride.