July 15 (Bloomberg) -- Lust and death in equal measure invade Hogwarts School of Witchcraft and Wizardry in “Harry Potter and the Half-Blood Prince,” the sixth and darkest installment in Warner Brothers’ adaptations of J.K. Rowling’s best-selling novels.

The film, directed by David Yates, who also made the last Potter picture, is a springboard to the final two, which Yates is also directing. Winding up for the finale, he thickens the atmosphere and uses quick edits, cluttered frames and skewed angles to convey the unsettling impact of puberty and mortality on Harry and friends.

Potter (Daniel Radcliffe) returns to Hogwarts shortly after the wizard community learns that his nemesis, Lord Voldemort -- “the most dangerous dark wizard of all time,” is back and wreaking havoc. Voldemort’s legions, the Death Eaters, are sowing terror, slaughtering wizard and non-wizard alike while the Ministry of Magic stands by helplessly.

Also, everybody is making out with the wrong person, which as any teenager knows is a disaster of its own kind.

Headmaster Albus Dumbledore (Michael Gambon) and Harry must get Voldemort’s old teacher to reveal the secret to the dark wizard’s power, even as sinister forces gather within the school. Steve Kloves’s dizzying screenplay delivers plenty of shocks and surprises, including a harrowing swarm of ravenous sea creatures and a deliciously psychopathic Helena Bonham Carter.

Finding Love

Through it all, schoolmates Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson) are sorting out their feelings for one another. Both actors have, well, grown since the previous films. Grint’s mugging has given way to comic timing, while Watson has gotten beyond her tic of following each line with a smirk or a scowl.

As Draco Malfoy, the sneering, blueblood whose greatest pleasure has been to torment Harry, Tom Felton stands out among the younger actors. The schoolyard bully is a reluctant successor to his father, a fallen Death Eater. Tall, tight-jawed and platinum-haired, Felton conveys almost wordlessly the burden and conflict of his wicked legacy.

Jim Broadbent joins the cast as Professor Slughorn, a dotty semi-retired Potions teacher who disguises himself as an armchair to avoid the Death Eaters. Alan Rickman returns, and nearly steals the movie, as Severus Snape. Snape doesn’t disguise his contempt for Harry -- whose father, James Potter, tormented him back in the day. Words drip from Rickman’s mouth basted in bile, and his buttoned-up black-clad presence looms like some Cromwellian nightmare.

Fully Formed

Dumbledore, who has watched over Harry most of the young wizard’s life, emerges at last a fully formed character, subtly urging Potter into adulthood.

The production seems to have grown up, too. Hungry monsters notwithstanding, the film’s grimmest, pivotal events unfold in austere surroundings, without the kinetic magic-wand duels that dominated earlier films.

As the intricately plotted and lavishly produced series hurtles to a close, Rowling’s achievement grows ever more apparent. The early novels and movies stood somewhere at the crossroads of “Tom Brown’s Schooldays,” “Star Wars” and “Scooby Doo.” “Prince” shows us children coping with the realization that life is a dangerous, finite journey. The more the characters reveal themselves, the more blurred the line between hero and villain becomes.

“Confused?” Dumbledore asks Harry. “I’d be surprised if you weren’t.”

“Harry Potter and the Half-Blood Prince,” from Warner Brothers, opens today in the U.S. Rating ****.

What the Stars Mean:
****          Excellent
***           Good
**            Average
*             Poor
(No stars)    Worthless

(Andrew Dunn is an editor at Bloomberg News. The opinions expressed are his own.)

To contact the writer on the story: Andrew Dunn in New York at adunn8@bloomberg.net.

Last Updated: July 14, 2009 22:30 EDT