Rosemary and Rue by Seanan McGuire

worst is death by iron. It kills the magic, then the mind, and finally the body. It’s the great leveler, the one thing that can kill anyone. Death by iron is slow, painful, and all too often inevitable.
    And the bastards killed her with it. It wasn’t enough that they’d invaded her privacy and ended her life: they had to make a show of it. What could she possibly have done to deserve that?
    A cop walked by, heading for the apartment, and muttered, “Rookie,” as he passed. I’d obviously hit him before, and he was still seeing me as whatever he wanted to see; good. The last thing I needed was questions about why I was kneeling outside a murder scene covered in blood when my head was still spinning.
    Even inside Evening’s memory, I hadn’t seen her killers. They’d somehow managed to keep themselves out of sight, or had erased themselves from the blood before they went. I didn’t know if that was possible, but I couldn’t discount it. These people were dangerous, and this was bigger than murder: someone used iron to end a life. Not just any life, either. The purebloods might have looked the other way if it had been a changeling, called it a “reprehensible affair” and left it alone . . . but Evening was one of them, born under the hills when mankind still thought fire was a neat new idea. The purebloods have their failings, but they look out for their own.
    If I didn’t move quickly, things were going to explode.

FIVE

    GOING BACK INTO THAT apartment took all the self-control I had, but I did it; I had to. I had heard three shots fired, and there were only two gunshot wounds on the “body.” That meant one of the bullets might still be somewhere in the room. If I wanted to be certain of the way that Evening died, I needed to find it.
    Iron bullets are heavy and uneven. That changes their ballistics; they can’t fly smoothly. Even if the police knew about the third bullet, they would’ve been starting their search from the shooter’s position with an incorrect idea of how far the bullet could have gone. I found it buried in the wainscoting of the wall across from the balcony, a small, uneven sphere that told me everything I needed and didn’t want to know.
    It was iron, pure enough to sting even from several feet away. I left it where it was and left the apartment for the last time. Physical evidence wasn’t required, and you can’t work sympathetic magic with iron. I’d just needed to know .
    The news van was still on the street as I walked back to my car, got inside, and pulled away, but the camera crew was nowhere in sight. That was good. My misdirection spells aren’t strong enough to stand up on film, and I didn’t want them recording me with blood caked on my hands and jeans.
    The iron told me two things: first, that Evening’s killers were fae, since no human would have used that particular weapon, and second, that I wasn’t dealing with any of the usual suspects. My own wounded sensibilities wanted to jump straight to the assumption that Simon and Oleander were involved, but they depended too much on magic to carry that much iron. They don’t have many scruples. That doesn’t mean they’d be willing to deaden their own magic for weeks, maybe even months, by having that much contact with iron. All that would do was get them caught, and they’re just too smart for that.
    Evening’s blood had its own share of information to impart, although it was a bit more nebulous in its usefulness. She didn’t call anyone else before she died; I was the only one who knew she was gone, other than the night-haunts—and her killers. Somehow I doubted the people who killed her would be spreading the news that they’d broken Oberon’s first law—the prohibition against killing purebloods except in formally declared war—and the night-haunts aren’t big conversationalists. I don’t even know anyone who’s actually seen them. I was on my own, and I was on a time limit, because I had to find her