I usually don't like comparing movies to their source books because the two are very different media and use different tools to interpret a story. And generally I find it a fault when a movie seems slavishly devoted to telling the story of the book it's adapting; the movie ought to have a life of its own. But with Harry Potter and the Half-Blood Prince, the first thought I had after viewing it was, "the book was better."

This is due to the film's shift in focus -- one I felt was carried through at the wrong time. Half-Blood Prince is the penultimate episode in the Harry Potter series, and while the first five books had each set up its own mystery or conflict to be solved through a rousing climax, the sixth book is notable for how much of it is devoted to prepping the reader for the upcoming final book. My main impression of the book, as I recall, was that most of the meat of the novel came from Harry visiting his mentor Dumbledore and learning the A to Z's of the history of his nemesis, the wicked sorcerer Voldemort. We learned about the villain's origins, his childhood, and the path he took to darkness; in terms of plot advancement, it introduced a crucial new element -- the next book's "MacGuffin," so to speak -- and then ended with a blindsiding twist.

The book felt like the least plotted of the Harry Potter adventures, but it was also obviously an extended set-up for what would become the final quest. Because the previous books hadn't dwelled too heavily on fleshing out Voldemort, the sixth book pretty much had to do it all in one sitting. I don't believe this was the wisest approach, but it gave the episode its defining characteristic. So what happens in the movie? Voldemort's history is barely viewed -- we get just two flashbacks of the young villain (Hero Fiennes-Tiffin and Frank Dillane, playing different ages).

Director David Yates and screenwriter Steve Kloves decided to focus more on the romantic entanglements of the teenagers. In terms of character interest, the decision is totally understandable, but I feel it was shown at the expense of the background of Voldemort, a character who has warranted more fleshing out and now has missed his best chance. J.K. Rowling, author of the books, did a commendable job running the two lines parallel; each had its own weight, with the teen hormone line being private life issues while the Voldemort line felt like real world issues. But Yates and Kloves minimize the investigation of the external threat and the advantage of having intelligence on a looming danger.

Technically speaking, though, Half-Blood Prince is a well-made movie. Yates's second outing in this franchise shows he's gotten quite comfortable at making this world his own, now dark with filtered lights, a generally gloomy place where the minor activities and interactions of your friends and families provide the warmth in an otherwise scary life. The movie becomes a dance between a teenage soap opera, with Harry (Daniel Radcliffe), Hermione (Emma Watson), and Ron (Rupert Grint) all coming to terms with certain romantic feelings they'd been harboring, and a horror movie, full of shadows, deadly incidents, and unfriendly figures. Standing alone, it's an involving portrait of an awkward stage of growing up, where teenagers are preoccupied with their emotions while the outside world and greater responsibility continually knock on the door.

So it takes the correct steps in forming an adaptation -- Harry Potter and the Half-Blood Prince, the movie, has its own concerns, concentrates on the themes it finds most interesting, and addresses only the details of the greater story it deems most practical in telling. On the whole, it's a fine film, and yet I'm disappointed that it didn't more greatly acknowledge the gravity of the impending conflict. Half-Blood Prince shouldn't be just another episode, and I wouldn't have thought it could have afforded to be just another episode. This is the one that should have set up the board, right before the final game, while firmly establishing the stakes. Although I enjoyed the movie, I didn't find the deeper weight of danger and dread I was hoping for.

(Released by Warner Bros. Pictures and rated  “PG” for scary images, some violence, language and mild sensuality.)

Review also posted at www.windowtothemovies.com .