Later that afternoon, Severus and his sister gathered in his living room to discuss the current situation.

“I don’t like this,” Saturnine said, crossing her arms over her chest. She stood near the fireplace and sported an expression that Severus could only qualify as petulant. It was a look he hadn’t seen on his sister’s face in years. It was her ‘I don’t want to eat my soup’ look.

“We don’t have a choice. We can’t risk anyone finding out,” Severus explained again from where he sat on his armchair.

“I’ve never lied to Harry,” she countered. “Not once. And I won’t start now.”

“Be selective about the truths that you share, then,” he offered. “Spin it in a way that—”

“Lying by omission is still lying, Severus,” she cut in.

One of his eyebrows rose in mock surprise. “Is it, now?”

“Yes, you snake—it is,” she replied, pacing the length of the fireplace back and forth.

That comment coming from anyone else would have angered him, but he knew she meant it endearingly, and he merely shrugged the comment off. “We agreed not to let anyone know.”

“But the boys wouldn’t tell a soul.”

“The Dark Lord has a direct connection to the inside of Harry’s head,” Severus pointed out.

“He knows how to Occlude,” Saturnine argued.

She waved an impatient hand about, and Severus all but rolled his eyes at her. As if that would help them. He knew how talented Voldemort was at Legilimency. And Harry, for all his good intentions, would be unable to stop him. “We can’t risk it, ’Nine. I won’t have it.”

“Fine, I’ll do my best.” She gave in with an exasperated huff. “But I make no promises if he comes at me and asks me straight up what I know with those imploring emerald puppy eyes of his.”

Severus would have snorted if he, too, didn’t find it difficult to stand up to Harry’s soul-searching green-eyed stare. “Minerva seems to have things under control for the moment,” he said, referring to the recent arrival of a bunch of Aurors at Hogwarts. They had secured the ‘crime scene’ and made all the necessary reports before removing the headmaster’s body.

Their plan had gone smoothly, and everyone had been fooled into thinking that Albus Dumbledore was dead. An official investigation into his murder was set to begin any day now. Apparently, it was only a matter of finding the right wizard or witch to lead it, and Severus feared that meant allowing a Death Eater into their midst.

Staff and students alike would be under scrutiny then, and they’d have to be careful what they did. Which was why they had better put what little freedom they had left to good use.

“We have retrieved one more Horcrux,” he said. “We need to hurry to find the other two.”

“I’ll go talk to the Grey Lady,” Saturnine offered. “See if she knows anything about the diadem.”

The Grey Lady, Helena, was a witch and Rowena Ravenclaw’s daughter. She attended Hogwarts centuries ago and was sorted into the house that her mother had founded. Shortly after her death, she returned as a ghost to Hogwarts Castle, where she became and continued to be the ghost of Ravenclaw House.

Slytherin House also had its ghost: a nobleman whose name had been forgotten over the centuries. Condemned to wander through the years covered in the silver bloodstains of one of his victims, he was now known solely by the moniker of “Bloody Baron”.

As ghosts went, the Baron was very pale, pearly-white, and slightly transparent. He had wide, staring black eyes and a gaunt face and carried chains in a final act of contrition for his past deeds. He was the worst of all the Hogwarts Ghosts—a truly despicable character.

The idea of sharing his space with living ghosts had been hard to accept for Severus when he first came to Hogwarts. No one had thought to warn him, and he’d nearly had a heart attack when he first met the Slytherin ghost. And to this day, being near the Baron still made him uneasy—not that he would ever admit that to anyone.

“Do you mind—” Severus started, “I mean if that’s okay with you…”

“Want to tag along?” Saturnine asked in understanding.

“You never know with these ghosts,” he said, and they were on their way to the ravens’ nest a few minutes later.

“In all my years of teaching at Hogwarts, I don’t think I’ve ever spoken with the ghost of Ravenclaw Tower,” Severus said as they climbed stair after stair up said tower.

“You’re not missing out on much,” Saturnine said. “She isn’t that pleasant to speak to.”

It was a lot of steps to get to the top, and they were both slightly breathless when they reached the last floor. “Do you know where to find her?” he asked.

“No. She randomly drifts about the entire tower and sometimes wanders into the rest of the castle,” she said, stopping by the entrance of the Ravenclaw quarters. “I thought we’d start up here and work our way down. If we can’t find her today, we’ll start again tomorrow.”

Severus nodded, cursing at the ghosts of Hogwarts that always seemed of a mind to make his life difficult. First that blasted Peeves, who liked to mess with his stores and Potions’ equipment—then the Bloody Baron that was a menace in himself and delighted in scarring his youngest snakes. And now there he was, stalking the corridors searching for a drifting damsel in white.

They caught sight of a tall ghost around a corner and froze. She drifted away through a solid wall before they had the time to get close. Once through the door of the corridor she had disappeared into, they saw her again. She was at the very end of the passage, still gliding smoothly away from them.

“Hey—wait—come back!” Saturnine called, rushing forward.

The ghost consented to pause, floating a few inches from the ground. She was beautiful, with her waist-length hair and floor-length cloak. But she also looked haughty and proud.

“Good afternoon, Grey Lady,” Saturnine said once she had reached her. She affected a polite bow of her head.

The ghost returned the gesture but did not speak.

“We apologise for disturbing your day,” she continued. “But we urgently need your wisdom.”

“We need to know anything you can tell us about the Lost Diadem,” Severus cut in. He never understood people who went out of their way to be mindful of the ghosts’ feelings. They were dead, for Merlin’s sake; their feelings couldn’t get hurt anymore.

A cold smile curved the ghost’s lips. “I am afraid,” she said, turning to leave, “that I cannot help you.”

“Please, Helena,” Saturnine said fiercely. “This is important. If the diadem is at Hogwarts, we must find it, fast.”

“Generations of students have badgered me about this,” she said disdainfully. “And you are not the first professors to covet the diadem, either.”

“You mistake us, Helena. We do not want it for its powers,” Severus cut in. “It’s about the war—defeating Voldemort—avenging the headmaster’s death. Or do you not care about that?”

Saturnine shot him a warning glare that clearly intimated he had better behave.

Ghosts could not blush, but Helena’s transparent cheeks became opaquer, and her voice was heated as she replied, “Of course I do—how dare you suggest that I don’t?”

“Well, help us, then!” he urged her.

The ghost’s composure was slipping. “It—it is not a question of—” she stammered. “My mother’s diadem…” She looked angry with herself. “While the diadem bestows wisdom,” she said, with an obvious effort to pull herself together, “I doubt that it would greatly increase your chances of defeating the wizard who calls himself Lord—”

“We are not interested in wearing it!” Severus cut in, feeling himself reaching the end of his patience. “If you care about Hogwarts and want to see Voldemort terminated, you’ve got to tell us everything you know about the diadem!”

The Grey Lady remained quite still, floating in mid-air, staring down at them, and a sense of hopelessness engulfed Severus. Of course, if she had known anything, she would have told Flitwick or Dumbledore, who had surely asked her the same question before.

“Please, Helena,” Saturnine said imploringly. “We need your help. The time is grave.”

“I stole the diadem from my mother,” she conceded in a low voice, as if reluctant to confess to her crime. “I sought to make myself cleverer, more important than my mother. I ran away with it.”

Both he and his sister listened with great attention, careful not to interrupt.

“My mother, they say, never admitted that the diadem was gone but pretended that she had it still. She concealed her loss, my dreadful betrayal, even from the other founders of Hogwarts. Then my mother fell ill—fatally ill. Despite my perfidy, she was desperate to see me one more time. She sent a man who had long loved me, though I spurned his advances, to find me. She knew that he would not rest until he had done so.” She drew a deep breath and threw back her head. “He tracked me to the forest where I was hiding. When I refused to return with him, he became violent. The Baron was always a hot-tempered man. Furious at my refusal, jealous of my freedom, he stabbed me.”

“The Baron?” Severus couldn’t help himself from asking. “You mean…”

“The Bloody Baron, yes,” said the Grey Lady, and she lifted aside the cloak she wore to reveal a single dark wound in her white chest. “When he saw what he had done, he was overcome with remorse. He took the weapon that had claimed my life and used it to kill himself. All these centuries later, he still wears his chains as an act of penitence—as he should,” she added bitterly.

“And—and the diadem?” Saturnine asked.

“It remained where I had hidden it when I heard the Baron blundering through the forest towards me—concealed inside a hollow tree.”

“A hollow tree?” repeated Saturnine. “What tree? Where was this?”

“A forest in Albania. A lonely place I thought was far beyond my mother’s reach.”

“Albania,” mused Severus. Sense was emerging from confusion, and now he understood why she was telling them what she had denied Dumbledore and Flitwick. “You’ve already told someone this story, haven’t you? To a student, long ago?”

The Grey Lady closed her eyes and nodded. “I had no idea. He was flattering. He seemed to—to understand, to sympathise…”

Yes, Severus thought, Tom Riddle would certainly have understood Helena Ravenclaw’s desire to possess fabulous objects to which she had little right. “Well, you weren’t the first person Riddle wormed things out of,” he muttered. “He could be charming when he wanted.”

So, Voldemort had managed to wheedle the location of the Lost Diadem out of the Grey Lady. He had travelled to that far-flung forest and retrieved it from its hiding place, perhaps as soon as he left Hogwarts—before he even started work at Borgin and Burkes. And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years? But the diadem, once it became his precious Horcrux, had not been left in that lowly tree. No, the diadem had been returned secretly to its true home, and Voldemort must have put it there.

“Do you know where the diadem is now, Helena?” Saturnine asked.

The ghost shook her pale head negatively. “I’m sorry, but I cannot help you more,” she said before floating gently away.

Generations of students had failed to find the diadem, which suggested that it was not in Ravenclaw Tower—but if not there, where? What hiding place had Tom Riddle discovered inside Hogwarts Castle that he believed would remain secret forever?