"THE CHAMBER OF SECRETS WILL BE OPENED."

Three sentences were etched into the exterior wall of Hogwarts early in the morning of Harry Potter Day, in enormous lettering, readable from Hagrid's hut. Smoke softly and endlessly drifted off of the letters, and the smell of burning was faintly present throughout the castle. The spell that had been used was clearly one of power, but Headmistress McGonagall could not identify it besides suggesting that it was ancient and had not been seen since the time of the Founders. Even Fiendfyre would not have been a satisfactory explanation; it was some more powerful variant of the basic cursed fire concept, a spell from which Fiendfyre had originally been derived.

"THE LINE OF MERLIN WILL BREAK."

Talk quickly spread, and even though the administration immediately threw a tarp over the relevant wall, the twenty words were repeated in whispers over and over, throughout the school and soon in the Daily Prophet. There was no escape for anyone from the mysterious smoking ultimatum. Who had made it? Why was it so threatening? Were they able to follow through? Most of the school was fascinated, but not particularly concerned – they were following Harry's lead, though he refused to elaborate on what about the threat he found particularly interesting, or on why he did not see it as a serious crisis. Still, the words loomed large:

"UNTIL IT DOES YOU ARE NOT SAFE."

"So, this story isn't quite true, either," said Ginny. "Can you name any obvious problems with it?"

"Um," said Draco, but he was not able to think of an inconsistency. He was reeling from the mere concept of the world nearly being ended by the dissatisfaction of the being who had created it. His hand ran over the animated illustration of the Ark rocking in the waves, tiny hands reaching up from the water, trying and failing to cling onto the side, desperately trying to save themselves. "I'm afraid you'll have to answer this one for me."

"Mostly just that it doesn't match up with reality," said Ginny. "A miraculous global flood of the proportions described would have left a distinct mark in the Earth's rocks; the Earth's rocks can be used to ascertain an accurate history of natural events on the Earth. There's no reason God would remove the evidence of the Flood, the common explanation is that it's a test of faith but I already explained why that's such an insidious lie. There are too many distinct species on the Earth for them to have all diverged recently from the inhabitants of one boat, even if that boat were many times larger than any we've been built. Not to mention that you need a much larger number of individuals than described to avoid a crippling genetic bottleneck. This is not a description of how human civilization survives and rebuilds from an apocalypse that nearly causes extinction. This is a description of how ancient, tribal humans imagine human civilization surviving and rebuilding from an apocalypse that nearly causes extinction."

"So it's a myth, then," said Draco. "A legend."

"Yes," said Ginny. "But a legend originating in truth. The story of Noah is the Jewish version of the Flood Myth. The Flood Myth is a story that appears in many world religions, all of which apparently came up with it independently. Each culture's version of the Flood Myth has different details, but it's essentially the same story. Wizard archaeologists know that the Flood Myth is fallout from the destruction of Atlantis. When Atlantis was lost in time, refugees managed to flee into history, and brought with them Atlantean knowledge and magic that made them important leaders wherever they landed. The most recent, of course, was Merlin, who founded modern wizarding society. I believe Noah and his family were also such refugees. Noah appeared alongside his wife and children, among the prehistoric Jews, and he became their patriarch."

"That makes sense," said Draco, "but I thought the Jews were all Muggles when Christ was born? Isn't that a major theological point?"

"Much time passed between the time of Noah and more solidly recorded times," said Ginny. "I think the most likely explanation is that magic slowly faded from their tribe as magical ability ceased to be valued, and was eventually instead feared. Some of the wizards descended from Noah bred into Squibs, and then Muggles, while others splintered off into separate strictly magical tribes."

"Does that mean you support blood purism?" said Draco, and Ginny wasn't sure whether to read his expression as suspicion or hope.

"No," said Ginny, "not at all. Just that I think it's possible to swing too far in the other direction."

"So did God destroy Atlantis?" asked Draco. "Or is that just part of the story, too?"

"I don't know," said Ginny. "It's certainly possible; that's one common interpretation of the story. A more mundane possible interpretation is that the Atlanteans did something foolish and destroyed themselves, as is the secular line of thought since at least Merlin, and the point of the story is that whatever foolish thing they did that eventually destroyed them was something God frowns upon. There are additional books in the appendix that go into more detail about Noah's ancestors and the society he originally came from – presumably Atlantis – but they're particularly cryptic, as echoes of Atlantis tend to be. The whole of magical history is a mess of time loops from Atlantis; Wizard Christianity posits a root cause of it all in Christ." Ginny glanced at a clock. "I think it's time we take a break."

"Okay," said Draco. "What do you think of the message?"

"It's about how disobeying God can be an existential threat to an entire society," said Ginny. "Which I think is a perfectly-"

"No," said Draco, "I mean the message," and she immediately knew what he meant.

"Oh – it's very shocking," said Ginny. She had actually seen it in person before it had been covered up, though it was all kind of blurry; she had left some kind of party on Halloween with a headache and had trouble sleeping. The following morning, when the ultimatum was revealed, she had still been sore. "But I don't know what to think of it. It's certainly a threat, but we have no idea if the anonymous messenger is actually able to follow through on it."

"They used powerful magic to carve that into the stone of Hogwarts," said Draco. "Especially since it's apparently prevented itself from being repaired."

"I suppose that's right," said Ginny. "But if it were really worth panicking about, don't you figure you'd see more people panicking? Nobody's been pulled out of school. No one looks like they're in fear for their life."

"I think not fearing for your life around now might be a serious mistake," said Draco. "It's possible that the threat is empty, but the reference to the Chamber of Secrets means that the threat is serious. The last time it was opened was when my grandparents were in Hogwarts; a student died. I seriously doubt the new Heir intends to do anything less."

"It's a good cause, at least," said Ginny. "I don't want anyone to die, but I actually kind of want to see a few people get hurt. What they want is for the Interdict Of Merlin to end, right?"

"That's the common interpretation," said Draco.

"Well, it'd be good if it did end, right?" said Ginny. "The Interdict Of Merlin is the biggest threat to magic; it's already lost most of the magic that existed a millennium ago."

"True," said Draco. "But whoever the good guys are, we're in the crossfire. Someone is going to be killed, soon, I can feel it and I'm not even a Seer. I'd rather that that not be me."

"Or me," said Ginny. Deep down, part of her would be willing to dispense with most of her peers if she knew it would end the Interdict. Some things were simply obviously barriers to progress that had to come down. But her moral component rejected this entirely. The bad guy in this equation was clearly whoever was blackmailing Hogwarts, and Ginny did stand against them, just not on all things.

According to every post-first year and several of the teachers, Professor Columbus was infinitely more exciting than Professor Binns had ever been ("probably even when he was alive", added a few). For this he was commended, but he was still not a perfect teacher. He was a bit dotty, far less mature than his aged appearance would indicate; he would often go off on tangents that, while informative and fascinating, had little to do with the main topic. For better or for worse, he was a fun teacher. On this particular day, he was six minutes late to class, and Colin Creevey was showing everyone photographs he'd managed to take of the Heir's Ultimatum before it had been hidden. Professor Columbus ran into the classroom, twisting his beard around a stick and muttering minced oaths under his breath.

"Alright, let's begin today's lesson," said Professor Columbus. "Or, rather, let's not. Let's talk about something else that's on everyone's mind. Something historic. Let's talk about the Chamber of Secrets." There were gasps. "Yes, yes, I know. Shocking. The Chamber is among Hogwarts' biggest mysteries, which is saying quite a lot, considering the storied history of Hogwarts. It's certainly the biggest mystery relating to Salazar Slytherin, and that's even considering that no one knows where he went after abandoning Hogwarts, or when or where or how he died. Some historians have suggested that he was likely entombed in the Chamber itself – perhaps accidentally, at that; several Dark Lords throughout history claim that they have been to the Chamber and it seemed that its construction was not complete. In fact, the testimony of Dark Lords are our only source of information about the Chamber's interior. The Chamber of Secrets is well-named, and most of its secrets have been well-kept, except for vague details."

"One of the most notable details is Slytherin's Monster," said Professor Columbus. "Some details are consistent between all descriptions of Slytherin's Monster, and other details are contradicted by assorted Dark Lords. But all descriptions of the Chamber include a reference to the Monster, for the Monster is the Chamber's primary feature. Slytherin's Monster is a creature of extreme longevity, born during Slytherin's lifespan and still alive today; all accounts agree on this, and that the purpose of the Chamber was to house it for its entire natural lifespan, which, while not necessarily eternity, would have been practically the same thing from Salazar's perspective. Most agree that the Monster is serpentine, so that it may be commanded exclusively by Parselmouths."

"This limits the potential form of the Monster considerably," said Professor Columbus. "Assuming, of course, that the Monster is a known creature and not some unique hybrid, chimera or construct that Slytherin invented exclusively for the Chamber, which is, admittedly, quite an assumption. But there are only two known serpents with lifespans sufficient for Slytherin's purposes – the Ashwinder, a snake relative of the phoenix, and the Basilisk, the legendary King of Serpents. Each explanation has pros and cons. The Ashwinder is truly undying, as opposed to the Basilisk, which merely has a lifespan dwarfing a human's. So Slytherin might have selected the Ashwinder in an attempt to grant his Chamber true permanency."

"But the Basilisk is a far more likely candidate," said Professor Columbus. "It's much more glorious, easily twenty feet long and attaining an unknown maximum size in its age. It's called the King of Serpents for a reason – it's by far one of the deadliest creatures in existence, not something you want to meet in a dark alley, though it's left off of most 'deadliest creatures' lists because they're so rare, one hasn't been seen in public in centuries. I doubt Slytherin would have been able to resist the allure of the Basilisk. The Basilisk theory was confirmed in 1943, although everyone refused to admit it at the time."

"Why do I say it was confirmed?" said Professor Columbus. "Very simple – a student was killed, and the cause of death was petrification. There are four creatures known to kill their victims by petrifying them. The Gorgon is not a plausible Monster. It has a normal human lifespan and was extinct in Slytherin's time. There are still no known means to recreate a Gorgon to this day. The cockatrice is not a plausible Monster. It lives little longer than a decade. The Acromantula is not a plausible Monster, for thematic reasons – it's a spider, not a serpent, and in fact it loathes serpents and will do anything in its power to destroy them; unless Salazar's entire affinity for snakes was a lifelong red herring, his Monster was not an Acromantula. And yet they claimed it was, at the time, in 1943, because there was a student on-campus known to have an Acromantula and it made for a quick conviction! An appalling failure of our justice system. No, the creature that killed Miss Myrtle Gale was clearly a Basilisk."

"The incident in 1943 also confirmed another theory about the Chamber," said Professor Columbus. "There was quite some debate over the purpose of the Chamber, prior to 1943. Some insisted that the Monster was a repository of Interdicted lore, designed to empower Slytherin's heirs with magical secrets that the rest of the world may well have forgotten. This is dubious, as it is not even known whether magical snakes may be used to bypass the Interdict in such a way; Merlin was no fool. In 1943, the competing theory was proven; that is, that the Monster was intended as a weapon to implement Slytherin's will. What is Slytherin's will, exactly?"

"In 1943, when the Chamber of Secrets was opened," said Professor Columbus, "messages were left by the Heir, indicating that he was fulfilling Salazar Slytherin's intent by purging the world of Muggleborn wizards. This was widely seen as plausible at the time, despite that it was the first anyone had heard of such a purpose. Salazar Slytherin was the most prejudiced of the Founders, but he still never hinted at genocide of any sort as a solution. Now, we are living through history. As you all know, a message was left this week; the official position of the Hogwarts administration is that it is most likely a bluff by a wrongheaded prankster, but we all know that that is calmheaded buffoonery."

"This message," said Professor Columbus, "by Slytherin's new heir, indicates a more congruous goal: to break the Line of Merlin Unbroken, ending the Interdict of Merlin as many have said Slytherin desired. It is still in line, though, with the notion that the Chamber and its Monster are a weapon of war, a war that we are just now beginning. How will that weapon be used? Who will win? What will happen? Who knows? We are at the beginning of a new chapter of history. I implore all of you to be careful, and now let's talk about goblin wars."

A week after the message originally appeared, smoke finally stopped pouring out of its enormous letters, in the middle of the night, about eight hours before Cedric Diggory's petrified body was found beneath it.