Knockturn Alley in HBP?
The link I mentioned between books two and six does not, in fact, relate to the Half-Blood Prince (because there is no trace of the HBP storyline in Chamber.) Rather, it relates to a discovery Harry made in Chamber that foreshadows something that he finds out in Prince.
The above quotation, straight from J.K. Rowling’s website, is one of the biggest hints we have to go off of right now about the plot of HBP. While we know now that analyzing CoS won’t get us any closer to figuring out the identity or importance of the HBP, the key here is a certain discovery in CoS that plays a larger role in HBP. I’m convinced that this discovery is (or is somewhere in) Knockturn Alley.
Taken by itself, the Knockturn Alley scene (p. 49-54 American CoS) is almost completely useless to the plot of CoS. It serves a minor purpose or two (for example, it arouses suspicion in Hagrid, and it introduces Lucius Malfoy), but the CoS plot certainly wouldnt be lacking if this scene were removed. It’s strange, then, that Rowling devotes half a chapter to it, or that it also made it into the movie (which we’ve been told holds some big hints for future books, too). Why write about Mr. Borgin or the Hand of Glory if Harry never sees them again and never goes back inside Knockturn Alley in the next 3 books? The only explanation: this scene is one of those ”Don’t pay attention as I throw in a few things that will become essential later on” clues that Rowling is famous for.
The question is: what is it in the Knockturn Alley scene thats going to turn out to be so important? To answer that, we need to look at the new things that get introduced while Harrys there.
The Hand of Glory: Seems unlikely to me. Why would you use the Hand of Glory to conceal light when you could just use an invisibility cloak to conceal yourself? It might show up again, but I think its just an example of a piece of dark magic, rather than, say, the cursed hand of the HBP (or some big revelation like that).
The Malfoys’ Manor: Harry sees Lucius Malfoy selling pieces of dark magic to Mr. Borgin because he’s afraid of Ministry raids, and we learn that there’s a lot more where that came from. Personally, I think that Lucius Malfoy’s involvement in dark magic and his mysterious manor will play a role in the final books, but this comes up many other times in the series. Doesn’t sound like something Rowling would write a whole useless scene just to convey.
Knockturn Alley’s existence: We don’t even know about Knockturn Alley until Harry lands there by accident. The alley in general might be the key to part of HBP. Maybe the something that he finds out in HBP has to do with dark magic in general, and Harry revisits Knockturn Alley to find more out about it. Or perhaps Knockturn Alley becomes a key meeting place for Death Eaters, or gets patrolled more closely by the Ministry because of its suspicious practices. These are all plausible, but then why is the visit to Borgin and Burke’s described in such detail? I think the link is more specific than this.
Mr. Borgin/Borgin & Burke’s: This is where I think the key to the HBP clue lies. First off: no, I don’t think Mr. Borgin is the HBP, partly because of Rowling’s statement above (its not directly related to the plot), and partly because he mentions the importance of pure blood while talking to Lucius Malfoy (p. 52). There are still a lot of questions that a character like Mr. Borgin could answer, though. We don’t know what happened to the rest of Harry’s family (magical grandparents, aunts, uncles, etc.); maybe Mr. Borgin does. Perhaps Mr. Borgin plays a role in Snape’s history, or maybe he even provided one of the means that Voldemort used to achieve immortality. Of course, with a shop named Borgin & Burke’s, we can assume that there is (or was) a character named Burke as well. He, too, might have played a role in any of these situations. At the very least, I think that Borgin & Burke’s could be the location of a key discovery in HBP, or of an important piece of dark magic.
I don’t think its possible to guess what Knockturn Alley has to do with HBP; after all, it would have been impossible to guess that Sirius Black would turn out to be a wrongly-convicted murderer and Harry’s godfather after reading the first chapter of SS. Keep a lookout, though, for the appearance of Mr. Borgin and Knockturn Alley in HBP.