“Right about now I assume you’re wondering why I’ve brought you here,” Albus Dumbledore says to Harry Potter in an early scene in Harry Potter and the Half-Blood Prince.

“Actually, sir,” Harry replies, “after all these years, I just sort of go with it.”

Well, after all these years, you either do or you don’t, and Half-Blood Prince is unlikely to change any minds in that respect. Potter fans, whether or not they’ve kept up with the books, will find that the latest film continues the trajectories of recent installments — it’s darker, more tragic and more romantic — while setting the stage for the final battle, now planned for two movies.

Director David Yates, whoseOrder of the Phoenix made the shortest film out of the longest book, is back, working for the first time with returning screenwriter Steve Kloves, who worked on every film but the last one. The book version of Half-Blood Prince is the first in the series to reverse the trend toward ever-longer page counts — it’s only the third longest of the first six books — and the movie version, possibly coincidentally, is the third longest of the six completed films.

As a result, for perhaps the first time since Alfonso Cuarón’s Prisoner of Azkaban, the third film in the series and one of the most popular, the characters don’t get short shrift. In Goblet of Fire, the fourth film and possibly the best adapted of the series to date, the characters suffered; Ron was a whiner and Hermione a shrill scold. They got better in Order of the Phoenix, which also gave Harry his best hero moments to date — but only now, in moments of calm before the storm, do Harry and his friends have room to breathe, to be themselves.

The romantic stirrings that felt rushed and perfunctory in the last two films (Ron’s lame attempt to ask Hermione to the Yule Ball, Harry’s irrelevant first kiss with Cho Chang) take center stage. Harry (Daniel Radcliffe) finally notices a girl who noticed him right from the start — his best friend Ron’s kid sister Ginny (Bonnie Wright) — but at the moment she’s carrying on with another admirer, much to Harry’s — and Ron’s — chagrin. Ron (Rupert Grint), with his exploits on the Quidditch field, attracts an enthusiastically amorous groupie, to the amusement of everyone except Hermione (Emma Watson), who has a thing for Ron.

I haven’t kept up with the books, but the Harry-Ginny thing makes sense to me: the young girl’s crush on her older brother’s best friend (in this case his famous and talented friend) to whom she, the best friend’s kid sister, is invisible, until suddenly one day she isn’t.

On the other hand, I don’t really buy the Hermione-Ron thing, at least as it plays out in the movies. Whatever Ron may be in the books, in the movies he’s mostly been comic relief at best, whiny annoyance at worst. Half-Blood Prince at least gives him a chance to be funny again, but it doesn’t let him show the sort of substance and strength of character that someone of Hermione’s standards would require in a beau.

Oh right, the war of good and evil. Well, it’s looking pretty bad. The story opens with Voldemort’s Death Eaters running amok, wreaking havoc in the Muggle world as well as the magical world, though they can’t get past the defenses that protect Hogwarts.

Inside Hogwarts, after mostly sitting out the last couple of films, Draco Malfoy (Tom Felton), whose father Lucius was exposed as a Death Eater and committed to Azkaban in the last film, is back with a vengeance. Is Draco in league with the Death Eaters? Is Professor Snape (Alan Rickman), who seems always to be on hand whenever Draco is under fire, a traitor protecting a traitor? Dumbledore insists that he trusts Snape, though Harry points out that Dumbledore can make mistakes and has admitted as much.

Trust, in fact, turns out to be a key theme of Half-Blood Prince. Mysteriously aloof for most of the last film, Dumbledore now openly relies on and confides in Harry — gratifyingly so, since Harry’s other adult mentor, his godfather Sirius Black, is dead, and there are intimations that even Dumbledore may not be around forever. Dumbledore cagily uses Harry to lure a former professor, potions master Horace Slughorn (newcomer Jim Broadbent, delightful as usual), back to Hogwarts, and urges Harry to win Slughorn’s trust in order to learn a secret Slughorn harbors regarding Voldemort’s schoolboy days as Tom Riddle.

Thanks to Slughorn’s class, Harry gets serious about studies for the first time pretty much ever, though once again he gets a free pass and takes the easy way. Harry inherits a used textbook extensively marked up, with brilliant corrections and invaluable additions, by a former student who went by the nom de plume “The Half-Blood Prince.”

With the help of the HBP cheat sheets, Harry quickly goes to the head of the class, and, in a violent confrontation, the book provides Harry with a startling edge. Here the movie skips a couple of links in the chain of thought that leads Harry’s friends (not Harry; he reverts to passivity here) to conclude that the book is too powerful or evil or something and needs to be hidden away forever.

Harry takes a more active role elsewhere, notably in a confrontation with Slughorn and in an affecting scene, one of the film’s best moments, in which Harry must carry out a heartbreakingly painful task in connection with Dumbledore.

In these scenes, loyalty to and trust in Dumbledore emerges as a defining moral trait for Harry — a trait emphasized at the climax in an interesting departure from the text. Judging from an online plot synopsis of the book, it seems that J.K. Rowling has Harry sidelined at the climax in such a way that he is a purely passive observer, not a moral agent. By contrast, in the film, Dumbledore allows Harry the dignity of a moral choice: one final dreadful test of his trust.

Whether the choice he makes is the right one is a question Harry must live with for the time being. What seems clear is that the loyalty Harry showed is the loyalty he can continue to expect from his friends as the war moves to the end game.

Steven D. Greydanus is editor and chief critic of DecentFilms.com.

CONTENT ADVISORY:Scary images, fantasy menace and violent magical battles; some passionate kissing and a few suggestive references; the death of an important supporting character under morally ambiguous circumstances. Teens and up.