stairs like What are you waiting for? I’m a wolf. I can’t open that hatch.

I climbed to the top of the stairs. The temperature was like the inside of a greenhouse. On the other side of the hatch, the wolf snuffled and chewed at the Plexiglas, leaving drool smears and fang marks. Those protective-barrier runes must have tasted great. Being this close to an enemy wolf made the hairs on the back of my neck do corkscrews.

What would happen if I opened the hatch? Would the runes kill me? Would they kill the wolf? Or would they deactivate if I let the wolf in of my own free will, since that was literally the stupidest thing I could do?

The wolf slavered at the Plexiglas.

“Hey, buddy,” I said.

Jack buzzed in my hand. “What?”

“Not you, Jack. I’m talking to the wolf.” I smiled at the beast, then remembered that showing teeth meant aggression to canines. I pouted instead. “I’m going to let you in. Won’t that be nice? Then you can get whatever you came for, since I know you’re not here to kill me, right?”

The wolf’s snarl was not reassuring.

“Okay, then,” I said. “One, two, three!”

I pushed against the hatch with all my einherji strength, shoving the wolf back as I surged onto the roof deck. I had time to register a barbecue grill, some planters overflowing with hibiscus, and two lounge chairs overlooking an amazing view of the Charles River. I wanted to slap Uncle Randolph for never telling me he had such a cool party spot.

The wolf stepped from behind the hatch and growled, its hackles raised like a shaggy dorsal fin. One of its eyes was swollen shut, the eyelid burned from contact with my uncle’s rune trap.

“Now?” Jack asked with no particular enthusiasm.

“Not yet.” I flexed my knees, ready to spring into action if necessary. I would show this wolf how well I could fight…or, you know, how fast I could run away, depending on what the situation called for.

The wolf regarded me with its one good eye. It snorted dismissively and bolted down the stairwell into the town house.

I wasn’t sure whether to be relieved or insulted.

I ran after it. By the time I reached the bottom of the stairs, Alex and the other wolf were having a snarl-off in the middle of the library. They bared their teeth and circled one another, looking for any signs of fear or weakness. The blue wolf was much larger. The neon wisps glowing in its fur gave it a certain cool factor. But it was also half-blind and wincing in pain. Alex, being Alex, showed no sign of being intimidated. He stood his ground as the other wolf edged around him.

Once our glowing blue visitor was confident Alex wasn’t going to attack, it raised its snout and sniffed the air. I expected it to run toward the bookshelves and chomp some secret book of nautical maps, or maybe a copy of How to Stop Loki’s Ship of Death in Three Easy Steps! Instead, the wolf lunged toward the fireplace, jumped at the mantel, and grabbed the mead horn in its mouth.

Some sluggish part of my brain thought, Hey, I should probably stop it.

Alex was way ahead of me. In one fluid movement, he morphed back into human form, stepped forward, and lashed out with his garrote like he was throwing a bowling ball. (Actually, it was a lot more graceful than that. I’d seen Alex bowl, and it wasn’t pretty.) The golden cord wrapped around the wolf’s neck. With one yank backward, Alex cured the wolf of any future headache problems.

The decapitated carcass flopped against the carpet. It began to sizzle, disintegrating until only the drinking horn and a few tufts of fur remained.

Jack’s blade turned heavier in my grip. “Well, fine,” he said. “I guess you didn’t need me after all. I’ll just go write some love poetry and cry a lot.” He shrank back into a runestone pendant.

Alex crouched next to the mead horn. “Any idea why a wolf would want a decorative drinking vessel?”

I knelt next to him, picked up the horn, and looked inside. Rolled up and crammed into the horn was a small leather book like a diary. I pulled it out and fanned the pages: drawings of Viking runes, interspersed with paragraphs written in Uncle Randolph’s cramped cursive.

“I think,” I said, “we’ve found the right dead white male author.”

We reclined in the lounge chairs on the roof deck.

While I flipped through my uncle’s notebook, trying to make sense of his frenzied rune drawings and cursive crazy talk, Alex relaxed and sipped guava juice from the mead horn.

Why Uncle Randolph kept guava juice in his library’s mini fridge, I couldn’t tell you.

Every so often, just to annoy me, Alex slurped with exaggerated gusto and smacked his lips. “Ahhhh.”

“Are you sure it’s safe to drink from that horn?” I asked. “It could be cursed or something.”

Alex grabbed his throat and pretended to choke. “Oh, no! I’m turning into a frog!”

“Please don’t.”

He pointed at the diary. “Any luck with that?”

I stared at the pages. Runes swam in front of my eyes. The notations were in a mix of languages: Old Norse, Swedish, and some I couldn’t begin to guess. Even the passages in English made little sense. I felt like I was trying to read an advanced quantum physics textbook backward in a mirror.

“Most of it’s over my head,” I admitted. “The earlier pages look like they’re about Randolph’s search for the Sword of Summer. I recognize some of the references. But here at the end…”

The last few pages were more hastily written. Randolph’s writing turned shaky and frantic. Splotches of dried blood freckled the paper. I remembered that, in the tomb of the Viking zombies in Provincetown, Randolph had gotten several of his fingers lopped off. These pages might have been written after that, with his nondominant hand. The watery cursive reminded me of the way I used to write back in elementary school, when my teacher forced me to use my right hand.

On the last page, Randolph had scratched my name: Magnus.

Under that, he’d sketched two serpents interlocking in a figure eight. The quality of the drawing was terrible, but I recognized the symbol. Alex had the same thing tattooed on the nape of his neck: the sign of Loki.

Below that was a term in what I assumed was Old Norse: mjöð. Then some notes in English: Might stop L. Whetstone of Bolverk > guards. Where?

That last word trailed downward, the question mark a desperate scrawl.

“What do you make of this?” I passed the book to Alex.

He frowned. “That’s my mom’s symbol, obviously.”

(You heard right. Loki was normally a male god, but he happened to be Alex’s mother. Long story.)

“And the rest of it?” I asked.

“This word looks like moo with a j. Perhaps Scandinavian cows have an accent?”

“I take it you don’t read Old Norse, then, or whatever that language is?”

“Magnus, it may shock you to learn that I do not have every talent in the world. Just most of the important ones.”

He squinted at the page. When he concentrated, the left corner of his mouth twitched like he was enjoying a secret joke. I found that tic distracting. I wanted to know what he found so funny.

“‘Might stop L,’” Alex read. “Let’s assume that’s Loki. ‘Whetstone of Bolverk.’ You think that’s the same thing as the Skofnung Stone?”

I shuddered. We’d lost the Skofnung Stone and Skofnung Sword during a wedding party in Loki’s cavern, when he’d escaped the bindings that had held him for a thousand years. (Oops. Our bad.) I never wanted to see that particular whetstone again.

“I hope not,” I said. “Ever heard the name Bolverk?”

“Nope.” Alex finished his guava juice. “I’m kind of digging this mead horn, though. You mind if I keep it?”

“All yours.” I found the idea of Alex taking a souvenir from my family mansion strangely pleasing. “So if Randolph wanted me to find that book, and Loki sent the wolves to get it before I could—”

Alex tossed the journal back to me. “Assuming what you just said is

true, and assuming it’s not a trap, and assuming those notes aren’t the ramblings of a madman?”

“Uh…yeah.”

“Then best-case scenario: Your uncle came up with an idea to stop Loki. It wasn’t something he could do himself, but he hoped you could. It involves a whetstone, a Bolverk, and possibly a Scandinavian cow.”

“When you put it like that, it doesn’t sound so promising.”

Alex poked the tip of the mead horn. “Sorry to burst your bubble, but most plans to stop Loki fail. We know this.”

The bitter edge in his voice surprised me.

“You’re thinking about your training sessions with Sam,” I guessed. “How are they going?”

Alex’s face told me the answer.

Among Loki’s many disturbing qualities, he could command his children to do whatever he wanted whenever they were in his presence, which made family reunions a real drag.

Alex was the exception. He’d somehow learned to resist Loki’s power, and for the past six weeks, he’d been trying to teach his half sister Samirah al-Abbas to do the same. The fact that neither of them talked much about their training suggested that it hadn’t been a rousing success.

“She’s trying,” Alex said. “It doesn’t make it easier that she’s…” He stopped himself.

“What?”

“Never mind. I promised not to talk about it.”

“Now I’m really curious. Is everything okay with her and Amir?”