When Harry entered the office, he rushed to Dumbledore's desk and almost slammed the diary onto it. Tonks came running up from behind and spoke in a fast, breathless manner over Harry.

"Sir, we found –"

"– Tom Riddle's diary!"

"But it's blank!" they both said, finishing the sentence together. Dumbledore leaned forward in a curious manner while surveying the diary. Then he drew his wand and waved a few non-verbal spells over it, though nothing happened.

"And?" said Tonks, almost quivering from excitement. "What's in there?"

Dumbledore shook his head. "I cannot be certain, though there appears to be an extraordinary amount of protection placed upon it." He opened the diary and paged through it. "Do tell me how you came upon this."

Harry told of how he and Tonks had found the diary in Myrtle's flooded bathroom.

"Myrtle?" Dumbledore asked, looking at Harry with a somewhat penetrating gaze behind his half-moon spectacles. "As in, the ghost formerly known as Myrtle Elizabeth Warren, from Ravenclaw?"

"Er ..." Harry felt as confused as everyone else. "I guess so. There's only one Myrtle-ghost around here, isn't there?"

Dumbledore dipped his luxury quill into a bottle of ink. Harry and Tonks rushed around the desk to see what Dumbledore was writing.

'Dear diary,'

To everyone's amazement, the words vanished as though sucked into the paper. The black ink reappeared with words Dumbledore had never written.

'Hello. My name is Tom Riddle. Might I ask who you are and how you came by my diary?'

"What?" Tonks blinked. "It's writing back?"

Dumbledore nodded. "Not unusual for a magical item. The question is, why would Lord Voldemort's belongings turn up in an abandoned bathroom?"

He wrote the words: 'I am an old friend, Tom. I believe your diary was found in a flooded bathroom.'

The words disappeared to be replaced by:

'Found by whom?'

'Harry Potter.'

There was a short pause before the diary replied with: 'I see. Which friend of mine are you, might I ask?'

"He doesn't seem to know who I am," Harry said, as Dumbledore paused to consider his options. "If this really is Voldemort's diary, well ... I'm surprised it hasn't attacked us yet."

"None of this makes sense!" said Tonks, frowning. "Maybe it's just a prank?"

"You should lie to it, sir," said Harry. "Don't tell him it's you."

Dumbledore shook his head. "Perhaps the truth – or partially so – would be more beneficial." Then he dipped his quill and wrote 'Albus Dumbledore.'

When nothing happened, Dumbledore kept his wand aimed at the diary while muttering a few spells. He kept this up until declaring that the diary wasn't about to attack them (or explode, as Tonks feared). Then he looked at one of the portraits on the walls.

"Professor Dippet," he said to a frail-looking old wizard, "can you recall Tom Riddle using this diary back in the day?"

"I cannot be sure, Dumbledore. Riddle was very secretive, if you might recall."

"Yes." Dumbledore sighed. "He certainly was."

At last, the diary responded with: 'I am glad to hear from you again, Professor. Is life treating you well?'

Harry scoffed. "Awfully nice for Lord Voldemort, isn't it? And here I thought it was a trap or something."

"Remember my words about Riddle's methods," said Dumbledore, pondering his next move. "This diary has yet to reveal its true purpose, whatever that may be."

Tonks agreed. "Mum told me about all sorts of weird artefacts. Her old family even had some robes which could strangle you."

Harry chuckled. "That's mental."

"Most of that family was, yeah."

Dumbledore carried on writing to the diary. He discussed the latest news in charms, Transfiguration, and the Dark Arts, after which he caught the diary off-guard with a question regarding the Chamber of Secrets.

'Ah yes,' wrote the diary, 'that old legend. I believe it was opened during my time at school, if you may recall. Is it true that the one responsible for that attack is now working at school?'

Harry blinked. "Wait, what?"

'At my request, yes,' wrote Dumbledore, before closing the diary.

"This confirms my suspicions," he said, looking even more pensive. "Voldemort has not used this diary in a long time. Its information is only partially accurate to the present, and not to the level I would expect from it."

Tonks looked puzzled. "So, is that a bad thing or what?"

"That remains to be seen," said Dumbledore, picking up the diary and examining it again. "If Voldemort has not used this in a long time, then how does it know about certain affairs of the present? We need to find out which person – be they student or not – has been providing it with information. This may lead us to the Chamber of Secrets."

"Let me guess," said Harry, staring at the diary, "I suppose we can't just ask it straight?"

Dumbledore shook his head. "It is well guarded, much like Riddle himself." Then he frowned. "But for what purpose would Voldemort have kept this diary around? If it had been to assist him in school, then why would it turn up in a girls' bathroom these days?"

Tonks gasped. "Of course! Maybe a girl was using it!"

"Well," said Dumbledore, amused, "that does seem rather likely. But then how did our suspect – or perhaps victim – obtain the diary in the first place?"

Harry thought back to Dobby's interferences. Not only had Dobby admitted to sealing off the magical barrier during the summer (which Mr and Mrs Tonks had an undercover Ministry-official repair), but he'd also ended up bewitching a Bludger after Harry. Both incidents had been Dobby's attempts at keeping Harry 'safe'.

"Maybe it has something to do with the Malfoys," Harry said, narrowing his eyes. "What if Dobby was ordered to bring it here?"

"Unlikely," said Dumbledore. "Remember that this is Voldemort and his supporters with whom we are dealing with."

But the more questions they asked, the less close they felt to the answer. Harry even asked about Riddle's alledged perpetrator, which Dumbledore revealed to be Hagrid.

"What?" Harry blinked.

"That's ridiculous!" said Tonks, equally shocked.

"Unfortunately," said Dumbledore, with a heavy sigh, "the evidence was damning in the eyes of the Ministry and Hogwarts. I have no doubt that Hagrid had been framed by Riddle."

Harry pondered their next move, then gasped. "What if we asked Myrtle about this? Wasn't she killed at school?"

"Yes," said Dumbledore, fixing his gaze on the diary. "But none of the heir's victims have been killed this time. I had thought about asking Miss Warren in the past but chose to leave it be. Perhaps I had even forgotten about her after a while."

Tonks rubbed her chin. "No sense putting it off now. Let's go."

They left the office and made their way through the corridors. Harry and Tonks were so excited over the Chamber of Secrets that they just couldn't help speaking out loud. And when they reached Myrtle's bathroom, they saw that Filch had already cleaned up most of the flood, and was now cleaning further down the corridor.

Myrtle was sitting on the cistern of the end toilet. She looked puzzled at the sight of Dumbledore.

"Hello, Miss Warren," Dumbledore said. "Would it be acceptable if we asked you a few questions pertaining your passing?"

Myrtle blinked. "Really? Hard to believe it's taken you this long, Professor."

"My apologies," said Dumbledore, though Myrtle seemed surprisingly calm. She even appeared flattered, after seeing Harry's interest. "Could you perhaps describe the incident?"

Myrtle hovered upright and began recalling her final moments with a relish in her voice. She mentioned dying in that very cubicle, and spoke at length about Olive Hornby and her teasing ("You remember Hornby, right?" she asked Dumbledore, who nodded). The next thing Myrtle remembered was hearing someone entering the bathroom and saying something funny ("A different language, I think it must have been"), after which she'd realised that it was a boy.

Riddle, no doubt, Harry thought.

"So I unlocked the door," Myrtle said, "to tell him to go and use his own toilet, and then ..." (she puffed out her chest, her face shining) "I died."

"How?" Harry asked.

"No idea," Myrtle said in a hushed tone. Then she recalled seeing a pair of great big yellow eyes, after which her whole body sort of seized up, and then she was floating away (she looked dreamily at Harry). "And then I came back again," Myrtle added, explaining about her determination to haunt Olive Hornby.

Harry looked around the bathroom. "Where exactly did you see the big yellow eyes?"

"Somewhere there," said Myrtle. She pointed in a vague manner towards the sink in front of her toilet.

Harry, Tonks, and Dumbledore rushed to examine the sink. They inspected every inch of it, including the pipes, until Harry spotted a tiny snake scratched on the side of one of the copper taps.

"That tap's never worked," Myrtle said brightly, when Harry tried opening it. Dumbledore leaned closer to inspect the tiny snake, and frowned.

"As expected. We may need Parseltongue to proceed."

Harry looked at Tonks in a nervous manner, then back at Dumbledore. "That's the snake language, right?"

"Quite correct," said Dumbledore, staring at the tap. "The problem is, I can only understand it, not speak it myself."

Tonks's mouth fell open. "You can understand Parseltongue?"

"Certainly," said Dumbledore, still scanning the tap, "but only after having spent a considerable amount of time studying it."

No sense in keeping it hidden here. "Erm, sir," said Harry, fidgeting with his fingers. "I can speak it."

Dumbledore froze for a moment before turning to face Harry. "I see. Well, forgive me if I am not too surprised by the revelation."

"How come?" Harry asked, but Dumbledore shook his head.

"That is a conversation for another time. For now, let us review our findings before proceeding." He began stroking his beard while voicing his thoughts. "I believe it is safe to assume that the monster within the Chamber of Secrets is a serpent. And given Miss Warren's description of great big yellow eyes, coupled with her immediate passing, I believe I have the answer."

Harry, Tonks, and Myrtle gave Dumbledore their utmost attention.

"The Basilisk is Salazar Slytherin's monster. It is known to have deadly venom and a fatal gaze."

"But everyone was petrified," said Tonks, looking puzzled, "not killed."

"Except me," said Myrtle in a deadpan manner. "So, let's hear it. What's the explanation?"

"Well, Mr Creevey saw the Basilisk through his camera, so perhaps indirect eye-contact results in petrification." Dumbledore paused for a moment. "And as Sir Nicholas is already deceased, perhaps he can only be petrified by direct eye-contact."

"And Mrs Norris?" Harry asked, beating Tonks to the question.

Dumbledore smiled. "There was a noticeable amount of water in the corridor. Mrs Norris likely saw the Basilisk's reflection in it."

After a short pause, Harry stared at the sink while speaking. "So we'll have to avoid looking at its eyes at all costs, then. How big is it?"

Dumbledore stared at the sink as well. "I cannot be sure. Basilisks may reach gigantic sizes, though ours seems to have found a way to navigate the school undetected."

"Maybe it's invisible?" asked Tonks, and Dumbledore shook his head.

"No, I believe it is using the pipes to travel. That would explain why Harry had difficulty locating the voice."

Harry nodded. "It came from the walls, now that I think about it."

"So," said Tonks, rubbing her hands together, "we going in now? Who knows what we'll find in there?"

While Dumbledore paused to consider their options, Myrtle gave a slight giggle.

"Harry, if you die down there, you're welcome to share my toilet."

Harry froze (and Tonks sniggered). "Er, I think we should get Professor McGonagall as well. Just in case."

"And Flitwick, too," said Tonks, still sniggering at Myrtle's offer. "He's a duelling champion, isn't he?"

Dumbledore shook his head. "Minerva should be enough."

Harry and Tonks left in a hurry. They ignored Filch and rushed down the opposite side of the corridor. It took them a few minutes to reach Professor McGonagall's office, which they did at around half-past seven.

"What is it this time?" Professor McGonagall asked in the doorway. She was looking down at Harry and Tonks in a scrutinising manner. "Not getting into more trouble, I hope?"

Harry opened his mouth to speak but was beaten to it by Tonks. She told of the Chamber of Secrets in a loud, exuberant manner; and said that Professor McGonagall ought to join them for another Gryffindor-adventure.

"I ... what?" Professor McGonagall blinked. "Is that how the two of you see it?"

"You bet!" Harry grinned. "Let's get that stupid Basilisk once and for all!"

"And maybe the heir, too!" Tonks added. Professor McGonagall paled.

"Wait. Did you say 'Basilisk', Potter?"

Harry nodded. "That's what Professor Dumbledore says it is. Now let's go kill Salazar's rubbish!"

Shaking her head in disbelief, Professor McGonagall followed Harry and Tonks through the corridor and up a staircase. They walked at a brisk pace before coming across Malfoy, Crabbe, Goyle, and Snape on the second floor.

"Can I help you, Professor Snape?" Professor McGonagall asked.

"Mr Malfoy has just told me a rather interesting story." Snape glanced at Harry, then back at Professor McGonagall. "According to him, he overheard Potter, Tonks, and even the Headmaster talking about the Chamber of Secrets earlier. Might I ask what this is about?"

Harry looked at the smug Malfoy, and frowned. "Got nothing better to do than to follow us around?"

Malfoy looked at Snape. "Professor, if they're after the Chamber and its heir, then we, as Slytherins, ought to be involved."

Professor McGonagall scoffed. "This does not concern you, Malfoy. Now run along or face punishment."

"I think not," said Snape, with a twisted smile. "Perhaps we can all come along to witness the dream team save our school again."

Harry clenched his fist. "It's bad enough bringing you along, Professor. But Malfoy and friends have to leave."

"Five points from Gryffindor, Potter," said Snape, glaring at Harry. "Professor McGonagall, I strongly recommend that you keep your students in line."

Malfoy, Crabbe, and Goyle sniggered behind Snape.

"You can accompany us to the Chamber," said Professor McGonagall, "though Malfoy and friends must leave. It is almost their curfew anyway."

"Shove off," Harry told Malfoy, with a smug grin. "You're not allowed here."

"Professor –"

"Leave it be, Draco," said Snape, interrupting Malfoy. "I will inform you of what has happened in the Chamber, in the common room."

Malfoy scowled. "Fine. But my father –"

"– 'will hear about this'," Tonks said in a mocking manner. "Blah, blah, blah. Get lost."

Still scowling, Malfoy stormed off along with Crabbe and Goyle. Harry felt a wave of loathing as Snape followed them to Myrtle's bathroom, where Dumbledore explained the situation.

"Excuse me?" said Professor McGonagall, when Dumbledore mentioned Harry's Parseltongue ability. Professor McGonagall was staring at Harry in a shocked manner, while Snape was giving Harry a shrewd and calculating look. "Are you sure?"

Dumbledore gestured to the copper tap which had the tiny snake scratched onto its side. "Harry, if you will …"

Harry approached the copper tap and stared at the tiny snake. It took him a few tries (and a lot of focus) to say 'open' in Parseltongue.

"But ... I don't understand!" said Professor McGonagall. "How can he possibly do that?"

Neither Dumbledore nor Snape seemed to have an answer. They remained silent as the tap glowed a brilliant white light and began to spin. Next second, the sink sank right out of sight, leaving a large pipe exposed.

"Interesting," said Dumbledore, surveying the pipe. "But first, a bit of discretion."

He flicked his wand and sent a bright ball of light down the pipe. It travelled so far that the pipe eventually turned dark again.

"Perhaps a different examination would suffice," said Dumbledore, still keeping his wand raised. "I would prefer that we not slide straight to the Basilisk."

There was a flash of fire in the middle of the bathroom, startling everyone but Dumbledore. They watched as Fawkes the phoenix dived into the pipe, glowing gold through the darkness.

"Wow!" said Tonks, blinking. "That was so cool!"

"Be quiet," said Snape, still staring at the pipe. "Or better yet, return to your dormitories. This is no place for distractions."

Harry clenched his jaw. "We're not going anywhere."

"Damn right," said Tonks, huffing.

Eventually, the pipe began filling up with an eerie, spine-tingling, unearthly music. It lifted the hair on Harry's scalp and made his heart feel twice as large. He felt ready for action, which was exactly what Dumbledore encouraged.

"That would be Fawkes," he said, gesturing to the pipe. "It is safe to proceed."

"For now," said Professor McGonagall. "Potter, Tonks, stay in sight at all times. If you hear any movement, cover your eyes at once."

"I'll go first," said Snape, striding ahead of Dumbledore. "This is, after all, Slytherin's Chamber."

Professor McGonagall rolled her eyes. She and the others watched as Snape slid down the pipe and out of sight. Then it was Dumbledore's turn to enter, followed by Harry, Tonks, and then Professor McGonagall bringing up the rear.

It was like rushing down an endless, slimy slide. Harry saw a number of pipes branching off in all directions, though none as large as theirs. The pipe twisted and turned, sloping downwards at a steep angle, and Harry knew that they were falling deeper below the school than even the dungeons. He could hear Tonks and Professor McGonagall coming up from behind, thudding slightly at the curves.

How much further?

All of a sudden, the pipe levelled out and deposited Harry, Tonks, and Professor McGonagall onto the damp floor of a dark stone tunnel. Dumbledore and Snape were already on their feet ahead, keeping their wands raised while standing in the golden light of Fawkes.

There was no time to stop and stare. Snape lit his wand and proceeded into the darkness ahead. He led the group through the tunnel and over several small-animal bones lying on the wet floor.

"Do you even know where you're going?" Tonks asked, and Snape ignored her. "We'll take that as a 'no', then."

While walking, Harry saw Tonks look up at Fawkes and smile. She screwed up her eyes in her usual, Metamorphosing expression and changed her long hair from ruby red to crimson.

Harry chuckled. "I like the other one better."

"Yeah, well, I want to match Fawkes, OK?"

Seconds later, they came across a large snake skin – at least twenty-feet long. It was a vivid, poisonous green, and was lying curled and empty across the tunnel floor. Dumbledore sent a burst of flame at the skin and set it alight.

"Good riddance," said Professor McGonagall, when the skin finally disintegrated after a while. "Let us do the same for the creature itself."

Eventually, around yet another bend, the tunnel ended at a solid wall on which two entwined serpents were carved. Their eyes were set with great, glinting emeralds.

"This," said Dumbledore at the wall, "is likely the Chamber of Secrets. Would you mind granting us access, Harry?"

Harry approached the wall, his throat very dry. It was easy to imagine that the snakes were real, given that their eyes looked strangely alive. As such, when Harry issued his command, he spoke in a low, faint hiss.

"Open."

Nobody said a word as the snakes parted and the wall cracked open. The halves slid smoothly out of sight, and Snape strode in ahead of the group.

"Imagine if he looked the Basilisk in the eye," Harry whispered to Tonks, who sniggered. Snape overheard them.

"Ten points from Gryffindor, Potter. You can tell all your friends how you lost them in the Chamber of Secrets itself."

They were now standing at the end of a very long, dimly lit chamber. Its ceiling was lost in darkness, supported by towering stone pillars entwined with more carved serpents. The pillars cast long black shadows through the odd, greenish gloom that filled the place.

"Proceed with caution," Dumbledore said. And as the group stepped forward, each of their footsteps echoed loudly off the shadowy walls. "Now, where might our reptilian foe be?"

When they drew level with the last line of pillars, they saw a statue as high as the chamber itself looming into view. Harry craned his neck to look up at the giant face above: it was ancient and monkey-like, with a long thin beard that fell almost to the bottom of the wizard's sweeping stone robes. Two enormous feet grey feet stuck out from the bottom of the robes, standing on the smooth chamber floor.

"Salazar Slytherin," said Snape, in a low, almost revering voice. "So many in our house would dream of this moment."

Harry scoffed. "How can they dream of it when they don't even know what the Chamber looks like?"

"Silence, Potter! Regardless of our mission, it is our duty to show one of our founders respect!"

Tonks cackled. "You should talk last about respect, Professor."

"Ten points from Gryffindor, Tonks!" said Snape, seething (while Dumbledore and Professor McGonagall looked amused at Tonks's words). "Now, where is that Basilisk?"

"Maybe in there?" Harry aimed his wand at the statue. "Let's smash it!"

"Yeah!" said Tonks, raising her wand as well. "Down with Slytherin and his Basilisk!"

Dumbledore stroked his beard (which was thicker than Slytherin's, it had to be said). "Could there be a secret entrance on it?"

Professor McGonagall frowned. "I must admit, for a place known as the Chamber of Secrets, there sure is a dearth of secrets to uncover."

"Why not ask Voldemort's diary?" Harry asked Dumbledore, and Snape paled.

"I wouldn't treat the Dark Lord's belongings like a joke!"

Dumbledore withdrew the diary from one of his cloak pockets. "Actually, I believe it would be better if you were to use it this time."

"Me?" Harry blinked. "But why?"

"You possess an advantage which I lack."

"And what's that?" Tonks asked, looking puzzled. "You're Albus Dumbledore!"

Dumbledore smiled. "And this is Harry Potter."

I think I understand. "OK," said Harry, reaching out for the diary. "But I'll, er, need a quill and ink."

"And a desk," said Dumbledore, waving his wand. He conjured a simple desk out of thin air, then withdrew a small bottle of ink and a deep-blue quill from a cloak pocket. "Riddle had – well, has a remarkable ego. Make of that what you will."

So Harry sat down and accepted the diary from Dumbledore. But just before he wrote, Harry looked at Dumbledore and asked, "Actually, why don't we just blow open the statue instead?"

Dumbledore shook his head, while looking at the statue. "Try the diary first and see what happens."

It was time to see whether or not Harry could goad Tom Riddle into giving up his information.