"Am I your valentine!?" squealed the ghost, face scrunching up in excitement behind her massive glasses, dark pigtails quivering.

I'd made a strategic investigation error.

There had still been no attacks since Pince was petrified, but I didn't think it was over with and I'd been working on leads. I'd remembered that Dumbledore mentioned "Ms. Warren" as the girl who died in the 40s under similar circumstances. It took a bit of research to track her down as Myrtle Warren, a bunch of dead ends trying to find documentation of her death, and then finally someone mentioned that "Moaning Myrtle" was a ghost that haunted a girls' bathroom: the same bathroom where Mrs. Norris was attacked.

I'd angrily made an appointment with Dumbledore just to yell about it.

The old wizard could only suggest that he'd tried to question the ghost several times over the decades, and she was highly irrational and unwilling to talk about it in any kind of sensible way. Most of his previous attempts had resulted in her throwing a tantrum and flooding the bathroom rather than giving up any useful information. He admitted he might have so relegated her to the back of his mind out of annoyance that he didn't even think about questioning her during the new crisis, but he invited me to do so.

He was, of course, not joining me.

The way the timing worked out, the first opportunity I had to talk to her after realizing I needed to was the Hogsmeade weekend for Valentine's Day. I'd thought about how there would be fewer people to object to me going into the second floor girls' bathroom on the Sunday without really thinking through the implications to a socially anxious ghost.

I was honestly surprised she still kept up with the calendar. Most ghosts didn't.

I would have done it Saturday, but I actually had to take my soon-going-to-have-to-admit-she's-my-girlfriend on a date. Things had gotten kind of tense, because it turned out picking a rumor fight with Maeve was a bad idea. I couldn't really tell people why they should be wary of her. She couldn't outright lie. It should have been an even fight. But I was way outgunned by someone used to sidhe politics. A school was no trouble. The fae princess had figured out what I was doing too fast, and started implying that I was sneaking out with her romantically and was complaining about her as a cover. I think she found the whole thing very amusing.

Mathilda didn't.

Fortunately, my basically-a-girlfriend was pretty smart, and even though I couldn't outright explain what was up with Maeve, I thought she was starting to figure it out from what I was able to say. Unfortunately, I'd kind of created a bunch of relationship insecurity by refusing to admit she was my girlfriend, so it was easy enough to assume I was looking to better-deal her with the impossibly beautiful new transfer student.

So, Saturday had to happen: big date day, lots of groveling, plenty of confidence-boosting.

And that was how I found myself stealing an hour on Sunday afternoon after a very coupley morning with Mathilda to go interrogate a ghost. A ghost who had immediately jumped to a shocking inference about my intentions. Honestly, it was less worrying than the school thinking I was having an affair with Maeve.

"Why don't we get to know each other first?" I hedged to the translucent teen witch hovering over the sinks and giving me what she thought was a sultry look. "You're Myrtle Warren, right? A Ravenclaw?"

She nodded. "And you're Harry Dresden. You're a Gryffindor. All the girls talk about you in here, you know? Talk about how tall and mysterious you are." Floating up to eye level with me, she looked down and fancifully twiddled her feet to show how far they were off the ground.

"I didn't actually know that," I groaned. "What else do they say?"

"They said you don't have a girlfriend, exactly, but maybe you have two girlfriends?" She was confused, and petulantly said, "I don't think you should date that new girl, Harry. She's mean. She froze my toilet once."

"We're definitely agreed on that. Those are just rumors that she's spreading. You should tell everyone." I suggested. "But I was curious about you."

"Oh?" the ghost managed to make a one-syllable expression last several seconds.

"Do you remember how you died?"

That was apparently the right question, which nobody had ever asked her. Amidst a tirade about some girl named Olive who she hated when alive and became a ghost to torment, she dropped some details about a boy speaking another language in the bathroom, and being paralyzed by yellow eyes that she thought killed her.

"You weren't turned into stone, though?" I asked. That was the first thing that seemed relevant.

"I don't think so? The other ghosts are mean to me because I was poisoned. You can't join any good ghost groups if you were poisoned. Not even in Rome, apparently, even with all the assassinations. I think it should count as death by magical beast, since it was acromantula venom. Which is funny, because I've never even seen one of those."

That would definitely jibe with the belief that an acromantula had been responsible. But something didn't add up. Did she see the spider and forget the part where it bit her? Or was she paralyzed and then poisoned? If it was afterward, she wouldn't know. While I thought about that, I asked, "Did you know Tom Riddle?"

"Oh! Tom!" she exhaled, floating up toward the ceiling and again drawing out each word. "He was so cute. He was tall, dark, and handsome like you… well, maybe not quite so tall. I wanted him to notice me so badly. That's why I spent so much time in here. He was in charge of installing the new toilets, you know?"

"I didn't know that," I admitted, thinking. "So you went to school here during the plumbing project? How did that work?"

She shrugged, the effort sending her floating up and backwards. "A lot of transfiguration. The whole school pitched in. The Ravenclaws had to figure out the best places where to put the pipes so they wouldn't break when the castle rearranged itself. And so professors wouldn't have to give up their favorite rooms. This used to be a privy room already, but there's a girls' toilet downstairs that was a storeroom. They didn't even take the lock off the door!"

"I'm familiar with that one," I agreed, it being where Hermione had spent the day before being attacked by a troll. The more important question was, "So Tom would have had access to basically everywhere in the school to route the pipes through? But he kept coming in here…"

"I think he was really proud of the sinks," she suggested, "even though one of them never worked."

The sinks were a pretty nice art deco arrangement of porcelain and copper, and were probably easy to be proud of before half a century of hard use in a haunted bathroom. One, indeed, didn't work, and careful examination revealed a glyph that looked like a snake etched onto the side of one of the copper taps. It wasn't a rune I recognized.

I made a little more small talk with Myrtle before extricating myself to go to the library. I was certain that if I could track down the meaning of that rune, it would give me more of a clue what was going on. I wondered if there might even be a network of them throughout the bathroom project, perhaps treating the entire plumbing system as one artificed array.

Ultimately, I probably would have saved a lot of time if I'd been thinking smaller.