Note: Thank you so much for bearing with me through my mad panic moment and my holidays. As a reward, here is a TRIPLE bill, albeit of slightly shorter chapters. Enjoy this first instalment and see if you can spot the Doctor Who reference.

Chapter Thirty-Two

Suspicion

Hermione was worried, on several counts. On the first count, there was a commotion going on at one end of the Ravenclaw table, and she couldn't help but wonder nervously what was going on. On the second count, Madame Pince had succeeded in finding some defence against the dark arts books, and some not quite so kosher magical texts, in a muggle bookshop in Wales of all places. Normally this would not be a cause for concern; in fact it should be cause for celebration, but having had a cursory perusal of Secrets of the Darkest Art, Hermione was convinced that her new-found knowledge of horcruxes had only served to make their quest even more impossible. Added to the pressing problem of the horcruxes was the difficulty of contacting the Order without being detected by the Ministry. Before Hermione had the chance to think on her situation any further, the kerfuffle at the end of the Ravenclaw table cleared and Professor Flitwick left the hall with a young first-year. She hadn't noticed the diminutive charms professor within the throng of students, and as she watched them leave, she wondered what had happened.

"Her parents were killed last night." Hermione turned to find Luna standing beside her. Her voice was neutral, sombre but matter-of-fact, but there was a sadness in her big, round eyes that betrayed the empathy she felt for her young housemate. "She's muggle-born. Why would he attack muggles for no reason, randomly? Just because he can?"

Hermione's blood ran cold, making her shiver. If it turned out that the muggles in question had been helping the resistance by supplying them with information, however unwittingly…

"What's her name?" Hermione asked, eventually getting her voice to work its way around the lump in her throat.

"Carrie Jones."

Hermione nodded unconsciously. It was as she had thought. They remained in silence for a moment, a mark of respect for the dead that also gave Hermione time to gather herself together once more, and then Luna spoke again.

"Hermione, have you noticed something different about Professor Vector lately?"

Hermione's heart sank. That was the final count of her worries. The old arithmancy teacher had been acting distinctly uncharacteristically ever since the beginning of the term. Although strict and uncompromising when it came to homework, she was not normally what one might call irritable soul, but she had been exceedingly ill-tempered of late, unable to make up her mind and blaming the class when they did the wrong thing having been told several different versions of a calculation. She had not been aware of it at first, blaming the odd behaviour on the stress of the zeitgeist in which they were fighting, but the strange quirks seemed to have only been accumulating over the past weeks. She had been considering the possibility of her place having been taken by an imposter under the influence of Polyjuice potion, and she had not quite gathered enough evidence to either prove or disprove her theory. Other, more pressing things kept getting in the way of her investigations. She nodded in answer to Luna's question, and posed one of her own. Maybe, if she could garner Luna's assistance in her investigations…

"Do you think it's really her?" she asked.

"Polyjuice, you mean?" asked Luna. "Like Moody in the third year?"

"Yes."

Luna shrugged.

"It's possible, I suppose. After all, that other one managed to get in here right under Professor Dumbledore's nose. If it is someone else though, they aren't doing a very good job of trying to blend in." Luna sighed and took the vacant place next to Hermione, picking at a piece of cold toast from the remains of the Gryffindors' breakfast. "We need to ask her a question that only Professor Vector would know."

Luna's logical solution to the problem was so simple that Hermione didn't know why she hadn't thought of it before. The only difficulty was finding something that only Vector, and not an interloper, would know. A complex equation was out of the question; surely anyone who wanted to make a halfway decent impression would have a working knowledge of the subject that they were proposing to teach.

"She'll be in her office," said Luna absently, spreading jam onto the toast with a spoon. "It's Saturday."

Hermione made her mind up then. They were going to find out the cause of Professor Vector's eccentricities once and for all, and they were going to do it now before anything else had a chance to push itself to the forefront of her mind and demand urgent attention. She turned to Luna.

"Shall we go and see her then?" she asked.

Luna smiled. Whilst so many wrote off the Ravenclaw as a couple of radishes short of a salad, Hermione knew that she had a practical and scheming mind when she needed to behind the vague visage.

"Why not?" She paused. "Have we got a plan as to what happens if it turns out that it is an imposter and she tries to kill us like the fake-Moody tried to kill Harry?"

Ah, thought Hermione. Trust the Ravenclaw to spot the obvious problem instead of charging in like a Gryffindor. There could be no doubt that Hermione would have got on well in Ravenclaw; the Sorting Hat itself had said so, but there were definitely times when she possessed the same blind and irrational courage that Harry and Ron so often displayed.

"Perhaps we should tell someone where we're going," suggested Luna placidly. "With a suitable excuse, of course. After all, we don't want the rumours that Professor Vector is actually a mad Death Eater running around the entire school now, do we?"

"No," Hermione agreed. She thought for a moment. "Ginny," she said to her neighbour, "Luna and I are going to talk to Professor Vector about the Skasis Paradigm. We'll be back for lunch."

Ginny nodded and returned to her toast.

"You do realise that the Skasis Paradigm doesn't actually exist," said Luna as they left the hall and made their way towards the seventh floor corridor where Professor Vector's office could be found.

"That doesn't mean we can't be going to talk to her about it," said Hermione. "We spend hours discussing fictitious works and other less-than-completely-real phenomena."

Luna nodded.

"Have we decided what we're going to ask her yet?"

Hermione didn't reply. Her mind had been trying to work on a suitable question ever since they left the hall, but the fact remained that she simply didn't know the arithmancy professor well enough to find anything that they had in common that she could ask about, and she continued to rack her brains all the way to her office door.

Luna took the simple initiative and knocked.

"Come in," snapped an irritable voice from behind the door. The two witches looked at each other for a moment with the unnatural tone and entered cautiously. Normally Professor Vector would never attempt to discourage someone who was seeking her assistance. Like all the other teachers, she was passionate about her obligation to help those with difficulties who wanted to succeed in her subject.

The professor in question was sitting at her desk with her head in her hands, but when she heard the dor click closed behind the two girls, she looked up at them over the top of her spectacles.

"Well?" she demanded.

"We were just wondering, Professor, if…" Hermione tailed off. We were just wondering if you are in fact an imposter in disguise and you're keeping the real professor in a wardrobe somewhere.

"I wanted to know if you could recall which question I got wrong on last year's exam," said Luna pleasantly. !I came to see you about it but I can't remember what it was."

It was a fairly ridiculous notion, but coming from Luna it was entirely plausible. Hermione half-wondered if her friend was in fact telling the truth.

!Do you expect me to remember every problem that every student comes to me with?" asked Professor Vector. "I always said that you had a memory like a sieve, Miss Lovegood."

Luna and Hermione looked at each other, and the seventh-year's hand went to her wand. The professor had dodged the question…

"The Vortex Protocol," said the elderly witch suddenly. "It was the Vortex Protocol. I remember it distinctly because you tried to explain the fundamental rules of arithmancy using wrackspurts as an example." She shook her head, and for a brief moment, her dour expression faded. "It was a most unique take on my subject," she said fondly, her voice faraway, as if she had forgotten the students' presence in the room.

Hermione looked at Luna, who nodded before shrugging her shoulders. After their initial suspicions, it was clear that Professor Vector was who she said she was and not a Death Eater or other malevolent presence. All they had to do now was to find the read cause of her out-of-character behaviour, something far easier said than done.

"Is there anything else you wanted, Miss Lovegood, or have you forgotten where the door is?"

"No, that's all. Thank you for your time, Professor."

They made to leave the room, but as they did so, Hermione caught a glimpse of something out of the corner of her eye. She twisted to look at it fully over her shoulder but it was gone, and she shrugged, passing it off as a trick of the light. As soon as she turned away, however, it glittered again, and she tried to focus on it without moving her head. The thing that had caught her eye was Professor Vector's pendant, sparkling in the sunlight. Except there was no sunlight. The day was bleak and grey outside the windows. The shimmer she had seen was the telltale shimmer that accompanied a magical glamour of concealment when viewed from the right angle; a giveaway that the item did not look exactly as it should.

"Come on Hermione," said Luna, nodding towards the door. "We've taken up enough of Professor's Vector's time.!

Hermione neither moved nor replied, trying to see the object behind the glamour, and her heart leapt to her mouth when she realised what it was and where she had seen it before. It was certainly not whilst it had been in Professor Vector's possession.

Time seemed to catch up with her in that moment, propelling her out of the door with Luna behind her.

"Are you alright?" the Ravenclaw asked, her voice concerned at the sudden change in her friend's demeanour.

"The locket," Hermione said faintly. "It's her locket."

"What about it?" asked Luna. "It's the same one she's always had."

"No, it's not," Hermione continued. "It's glamoured." She paused, unable to believe what she had seen with her own two eyes. "I've got to tell Harry and Ron. See you later, Luna."

She set off in the direction of Gryffindor tower at a sprint, leaving Luna behind, seemingly unfazed by her sudden abandonment. Hermione did not stop running until she reached the boys' dormitory, where Harry and Ron were discussing tactics for the forthcoming quidditch match against Hufflepuff.

"I've found it," she said, collapsing onto Neville's bed to get her breath back. "I've found the horcrux."

"What? Which one? Where? Who?"

The questions tumbled forth from the boys' lips in a torrent of excitement and disbelief.

"The locket," Hermione gasped. "It's round the neck of Professor Vector. She's been wearing the blessed thing all year."

Disclaimer: Credit to Garth Nix: the idea of only being able to see the truth out of the corner of your eye comes from his 'Keys to the Kingdom' series. I've used it quite a bit in various fanfics over the years; it's such a nifty little concept. I think he also came up with the concept of glamouring as well.

Note2: Onwards and upwards!