If 2001's "Harry Potter and the Sorcerer's Stone" and 2002's "Harry Potter and the Chamber of Secrets" were innocuous, child-skewing precursors to the gradually richer, smarter pleasures of 2004's "Harry Potter and the Prisoner of Azkaban," 2005's "Harry Potter and the Goblet of Fire," and 2007's "Harry Potter and the Order of the Phoenix," then "Harry Potter and the Half-Blood Prince" goes one step further (and several shades darker) as it noticeably matures along with its pubescent characters. Based on the sixth novel in J.K. Rowling's insanely popular fantasy series, this chillingly great, masterfully economical adaptation plays like a Greek tragedy in the epic tradition. Don't let the softer PG rating fool you, either (the fourth and fifth films were PG-13); this is far and away the most grim and violent entry thus far (there is a lot of blood and some sexual innuendo, too).

As Lord Voldemort's devious troops, the Death Eaters, begin to wreak havoc in the magical and muggle worlds alike, 16-year-old Harry Potter (Daniel Radcliffe) returns for his sixth year at Hogwarts School of Witchcraft and Wizardry. With word spreading that Harry might be "the chosen one" to ultimately do battle with the Dark Lord, he and best friends Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson) are also faced with intensifying growing pains and an increased interest in the opposite sex. Harry's flirtations with Ginny Weasley (Bonnie Wright) and Hermione's jealousy over Ron's bubbly new girlfriend Lavender Brown (Jessie Cave) coincide with rising dangers around the campus. Knowing that it is Harry's destiny to fight Voldemort, Professor Albus Dumbledore (Michael Gambon) gives him what he hopes will be an insightful peek into the saved memories between himself and childhood Voldemort alias Tom Riddle. As the Death Eater's close in, Harry has growing reason to believe Hogwarts archnemesis Draco Malfoy (Tom Felton) and Professor Severus Snape (Alan Rickman) are working in cahoots with them.

As the characters continue to grow up and deepen in their multiple facets, so, too, does a monumental franchise that keeps getting better and better. "Harry Potter and the Half-Blood Prince" is a remarkable achievement in imagination, storytelling, and underlying thematic relevance, a motion picture that visually dazzles as any respectably made blockbuster should, but also knows not to misplace the human element at the forefront. Director David Yates and screenwriter Steve Kloves refuse to shy away from the seriousness of their subject matter, painting the sumptuously layered plot, the provocatively dimensional characters, and the various touchy relationships with an unblinking naturalism that stabilize their more fantastical components.

Harry, Ron and Hermione are still making their way through the thickets of coming-of-age, but their sixth year at Hogwarts marks a turning point for them. With Hermione barely able to shield her feelings for Ron, Ron cluelessly choosing to go out with adoring groupie Lavender after he becomes hero of the season's Quidditch games, and Harry stuck in the middle while grappling with his own attraction to Ron's younger sister Ginny, the trio of tight-knit friends are about to receive a loud and clear wake-up call. Faced with their own mortality and that of those around them, Harry, Ron and Hermione are destined to make some very serious choices—choices that not only test their strength, courage, willpower and magical know-how, but will strip them forever of their childhood innocence.

Mixing relatable teenage conflicts with the alternate tone of a mood-induced thriller, director David Yates scarcely steps wrong. The complicated interpersonal ins and outs of the Hogwarts roster of students never gets squishy or sappy, but does register with a bittersweet poignance actualized first and foremost in Hermione's purely platonic, purely lovely connection to Harry when her yearnings for Ron are left out in the cold and frustratingly unreciprocated. For Harry, who has been sitting from afar while Ginny snogs with Dean Thomas (Alfie Enoch), he knows exactly what Hermione is going through. Lavender Brown, meanwhile, is blind with an infatuation for Ron that is just that, and nothing more. There is no substance beneath their whirlwind romance, and unfortunately only one-half of the couple recognizes this.

Lest it seem as if "Harry Potter and the Half-Blood Prince" is preoccupied with ways of the heart, the film reverberates in scene after scene with an unstoppable imminent threat. The opening action set-piece, depicting the deadly damage on London caused by the invading Death Eaters, is awe-inspiring in its grandeur and positively thrilling in its technical creativity and marvelous camerawork by Bruno Delbonnel (2007's "Across the Universe"). A sequence where Harry follows Draco through the shadowy hallways and dimly lit rooms of Hogwarts looks and sounds like something Alfred Hitchcock would be proud of, the classically atmospheric music score by Nicholas Hooper proving unforgettable here and throughout. Harry's glimpses into the memories of Dumbledore and Tom Riddle, the latter a kid whose disturbed mind and sheer intellect suggest of his evil future to come, are inherently creepy. The final thirty minutes, though, are its bread and butter, sweeping Harry and Dumbledore off to stormy seascapes and voluminous caves in search of a Horcrux—a hidden piece of Lord Voldemort's soul that, left undestroyed, renders him indestructable. Breathless suspense and a lingering genuine scariness reach crescendos that only the very best horror movies can attest to, and the culminating sacrifices and fates that follow (one central character dies at the wand of another) are superbly brought to full dramatic fruition. From this point on, for the survivors, nothing will ever be the same again.

Over the last eight years, it has been a treat watching Daniel Radcliffe (2007's "December Boys"), Emma Watson (2008's "The Tale of Despereaux"), and Rupert Grint (2006's "Driving Lessons") transform from novice child performers with a lot yet to learn into confident young adults with the honest, on-target intuitions of genuinely fine actors. By now, Radcliffe is Harry Potter, Watson is Hermione Granger, and Grint is Ron Weasley. They know these characters about as well as creator J.K. Rowling does, and the scattered, always truthful notes each one plays at any given moment are stunning to behold. Screenwriter Steve Kloves additionally treats these friends with a layer of dreams, desires and uncertainties disconnected to the central plot but crucial to exploring who they are on the inside and out, and the actors run with the chance to be more than pawns in a bigger picture.

The standout of the overflowing ensemble is Michael Gambon (2006's "The Omen"), whose Professor Albus Dumbledore is almost as much of a main character this time as Harry is. Dumbledore hates to ask so much of his pupil, but he also knows he must if he wants to protect everyone and everything that he has dedicated his life and career to. In the wise, wearied eyes of Gambon's Dumbledore is a man who has, in many ways, made his peace and is prepared to accept whatever is meant to be. It is a strong, shattering performance. As new potions master Professor Horarce Slughorn, Jim Broadbent (2009's "Inkheart") is appropriately quirky and mysterious, a man whose past with Tom Riddle is intentionally cloaked in obscurity. Maggie Smith (2002's "Divine Secrets of the Ya-Ya Sisterhood") is regal and earnest as always as Professor Minerva McGonagall, getting a welcome increase in screen time. Alan Rickman (2008's "Bottle Shock") is at his slimy best in his reading of Professor Severus Snape. And finally, Tom Felton makes good with his more prominent role as Draco Malfoy, painting a window into a conflicted soul not quite as dark as one might suspect.

Following a thunderous, game-changing climax, "Harry Potter and the Half-Blood Prince" winds down quietly and ruminatively, the exquisite, heartbreaking calm before the real storm. With their final year at Hogwarts before them but unlikely to be attended, Harry, Hermione and Ron stand in a now-shattered school that has, over the last six years, become their home. Now, in its own way, it no longer is, and never will be again. Upon Hermione professing her loyalty to Harry as his harshest tasks yet loom before him, he looks out from the Hogwarts tower and remarks, "I never realized how beautiful this place was." As with childhood, as with high school, as with life, it's all fleeting. You don't know what you've got 'til it's gone. Isn't that the damn of it?