First, there was the teaser trailer in July, then the international trailer helped tide us over last month. But finally, on Friday (November 14), the full proper U.S. trailer for "Harry Potter and the Half-Blood Prince" arrived, a week before the movie was originally set to hit theaters.

Posted first on fan sites such as the Leaky Cauldron, the trailer contains some of the same scenes as the previous clips, but it's the first to provide a sense of the film's balance between light and dark moments, including a choice one featuring a love-struck Ron Weasley.

Where the first teaser trailer from "Half-Blood Prince" focused on a young Tom Riddle, the boy who was to become Voldemort, and the international trailer on climatic battles between good and evil forces, this one provides a tad more exposition about Harry's quest-to-come: finding Voldemort's Horcruxes, the artifacts in which he's hidden pieces of his soul.

Before Dumbledore can tell us what a Horcrux is, he has to flash back and share with Harry the memories he's collected in his Pensieve. Dumbledore has been collecting them a long time, but there's one he needs in order to verify that he's correct in his theory about Voldemort, and only Harry can get this one.

Enter Professor Slughorn. "You are of course wondering why I brought you here tonight," Dumbledore tells Harry in front of the retired professor's cottage, where they've gone to coax him out of retirement. As you know, every year, Hogwarts loses its Defense Against the Dark Arts teacher, but this time, they have a new post to fill: Potions.

Slughorn, played by Jim Broadbent, instructs his students (including Lavender Brown, played by Jessie Cave) about some new potions, including one for luck and one for love.

"What you see before you is a curious little potion," Slughorn says. "It does cause a powerful infatuation or obsession." (This leads to a hilarious sequence in which Ron mistakenly eats the chocolate cauldrons Romilda Vane meant for Harry and falls madly in love with her. "All right, fine, you're in love with her," Harry says, trying to talk some sense into him. "Have you actually ever met her?" "No, can you introduce me?")

Slughorn hasn't been recruited merely for his teaching ability, but for a certain memory of his. Dumbledore tried to retrieve it from him once before, telling Harry, "This is the most important memory I've collected. ... It is also a lie." That Slughorn altered his memory before giving it to Dumbledore — an effect we see as swirling darkness as Slughorn tells a teenage Tom Riddle, "Now get out of here at once!" — signals that there was something to hide. Dumbledore needs Harry to get to the truth, since Slughorn (as well as some of the students) now hold a certain fascination with him, thinking he's the "Chosen One." (Hermione whacks Harry on the head with a newspaper when he jokingly refers to himself as that. "OK, sorry, kidding," he pleads).

It's in Slughorn's memory that we learn how much Riddle already knows about Horcruxes — one of the darkest magics — and how many times he's planning to split his soul. Dumbledore's already retrieved one and destroyed it, but another memory seen in the Pensieve reveals the location of another — a cave where Riddle used to torture other kids in the orphanage. The shots of Harry and Dumbledore outside the cave — which can only be entered by magic — and inside, where they fight for their lives against the Inferi, Voldemort's zombie-like guards, are stunning.

But the fight has only just begun — as glimpsed by the repeated scenes of the school's Astronomy Tower, over which is floating the Dark Mark. While Dumbledore and Harry were away, the Death Eaters came to play. What happens there, and who dies there, is foreshadowed in the trailer: Ron's falls down after being accidentally poisoned in Slughorn's office; Draco Malfoy examines himself in a mirror; and Harry chases Snape off the school grounds. "Fight back, you coward!" he yells, as Snape turns to face him.

The scenes shown over the crucial "fight back" taunt, however, also reveal that the werewolf Fenrir Greyback is present in the added Burrow fight scene. And it's not just the wizarding world being affected — a bridge in London is also destroyed, which means we'll likely get the scene where the Minister of Magic informs the Prime Minister of the goings-on.

There's not much room for young love in all of that, but the shot of Ginny and Harry leaning in for a kiss means there at least will be some glimpse of sunnier days ahead.

Check out everything we've got on "Harry Potter and the Half-Blood Prince."

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