Somehow, I’d lost my sunglasses from Alfheim. I doubted they would’ve helped, though. This light was intense in a different way. The colors made my eyes throb like twin hearts. The heat seemed to swirl a millimeter from my skin. Under our feet, the bridge made a low-pitched rumble like the recording of an explosion played on a loop. I supposed Halfborn Gunderson was right: without Heimdall’s blessing, we would have been vaporized the moment we set foot on the Bifrost.

Behind us, the cityscape of Boston became an indistinct blur. The sky turned black and full of stars like I used to see on my old hiking trips with my mom. The memory caught in my throat. I thought about the smell of campfires and toasting marshmallows, Mom and I telling each other stories, making up new constellations like the Twinkie and the Wombat and laughing ourselves silly.

We walked for so long, I began to wonder if there was anything at the other end of the rainbow. Forget pots of gold and leprechauns. Forget Asgard. Maybe this was a practical joke. Heimdall might just cause the Bifrost to disappear and leave us floating in the void. YOU’RE RIGHT, his squeaky voice would announce. WE DON’T EXIST. LOL!

Gradually the darkness grayed. On the horizon rose the skyline of another city: gleaming walls, golden gates, and behind them, the spires and domes of the gods’ palaces. I’d only seen Asgard once before, from the inside, looking out a window in Valhalla. From a distance, it was even more impressive. I imagined charging up this bridge with an invading army of giants. I was pretty sure I’d lose hope when I saw that vast fortress.

And standing on the bridge in front of us, his legs planted wide, was a tall warrior with a huge sword.

I’d imagined a god who was suave and cool—a movie-star type. Real-life Heimdall was kind of a disappointment. He wore a padded cloth tunic and woolly leggings, all beige so he picked up the colors of the Bifrost. It was camouflage, I realized—the perfect way to blend into a rainbow. His hair was white-blond and fuzzy like ram’s wool. His grinning face was darkly tanned, which might have been the result of standing on a radioactive bridge for thousands of years. I hoped he didn’t plan on having kids someday.

In general, he looked like that goofy guy you didn’t want to sit next to on the school bus, except for two things: his unsheathed sword, which was almost as tall as he was, and the huge curled ram’s horn slung over his left shoulder. The horn and sword looked imposing, though they were both so large they kept knocking into one another. I got the feeling that if Heimdall killed you, it would only be because he got clumsy and tripped.

As we approached, he waved enthusiastically, making his sword and horn bang into one another: clink, donk, clink, donk. “What’s up, guys?”

The four of us stopped. Sam bowed. “Lord Heimdall.”

Alex looked at her like, Lord?

Next to me, Amir pinched the bridge of his nose. “I cannot believe what I’m seeing.”

Heimdall arched his fluffy eyebrows. His irises were rings of pure alabaster. “Ooh, what are you seeing?” He gazed past us into the void. “You mean the guy in Cincinnati with the gun? No, he’s okay. He’s just going to the firing range. Or do you mean that fire giant in Muspellheim? He is coming this way…No, hold on. He tripped! That was hilarious! I wish I’d Vined that.”

I tried to follow Heimdall’s gaze, but I saw nothing but empty space and stars. “What are you—?”

“My eyesight is really good,” explained the god. “I can see into all of the Nine Worlds. And my hearing! I was listening to you guys argue on that rooftop from all the way up here. That’s why I decided to throw you a rainbow.”

Samirah gulped. “You, ah, heard us arguing?”

Heimdall smiled. “The whole thing. You two are just too cute. In fact, could I get a selfie with you before we talk business?”

Amir said, “Uh—”

“Great!” Heimdall fumbled with his horn and his sword.

“Do you need some help?” I asked.

“No, no, I got it.”

Alex Fierro sidled up next to me. “Besides, that wouldn’t be nearly as funny.”

“I can hear you, Alex,” the god warned. “I can hear corn growing five hundred miles away. I can hear frost giants belching in their castles in Jotunheim. I can definitely hear you. But not to worry, I take selfies all the time. Now let’s see…”

He fiddled with his massive ram’s horn as if looking for a button. Meanwhile, his sword rested at a precarious angle in the crook of his arm, the six-foot-long blade leaning toward us. I wondered what Jack would think of that sword, whether it was a hot lady or a professional linebacker or maybe both.

“Aha!” Heimdall must have found the right button. His horn shrank into the largest smartphone I’d ever seen, its screen the size of a Sicilian pizza square, its case made of shiny ram’s horn.

“Your horn is a phone?” Amir asked.

“I think technically it’s a phablet,” Heimdall said. “But yes, this is Gjallar, the Horn and/or Phablet of Doomsday! I blow this baby once, the gods know there’s trouble in Asgard and they come running. I blow it twice, then it’s Ragnarok, baby!” He seemed delighted by the idea that he could signal the start of the final battle that destroyed the Nine Worlds. “Most of the time, I just use it for photos and texting and whatnot.”

“That’s not scary at all,” Alex said.

Heimdall laughed. “You have no idea. Once, I butt-dialed the apocalypse? So embarrassing. I had to text everybody on my contacts list, like, False alarm! A lot of gods came running anyway. I made this GIF of them charging up the Bifrost and then realizing there was no battle. Priceless.”

Amir blinked repeatedly, perhaps because Heimdall was a moist talker. “You are in charge of Doomsday. You’re really a—a—”

“An Aesir?” Heimdall said. “Yep, I’m one of Odin’s sons! But between us, Amir, I think Samirah is right.” He leaned in so the people in the cornfields five hundred miles away couldn’t hear him. “Frankly, I don’t think of us as gods, either. I mean, once you’ve seen Thor passed out on the floor, or Odin in his bathrobe, yelling at Frigg because she used his toothbrush…it’s hard to see much divinity in my family. Like my moms used to say—”

“Moms, plural?” Amir asked.

“Yeah. I was born of nine mothers.”

“How—?”

“Don’t ask. It’s a pain on Mother’s Day. Nine different phone calls. Nine flower bouquets. When I was a kid, trying to cook nine breakfasts-in-beds…oh, man! Anyway, let’s get this picture.”

He corralled Sam and Amir, who looked stunned to have the grinning face of a god wedged between them. Heimdall held out his phablet, but his arm wasn’t long enough.

I cleared my throat. “You sure you don’t want me to—?”

“No, no! No one can hold the mighty phablet Gjallar except me. But it’s fine! Time-out for a second, guys.” Heimdall stepped back and fumbled with his phone and sword some more, apparently trying to attach them to each other. After a bit of awkward maneuvering (and probably several butt calls to the apocalypse), he held out the sword in triumph, the phablet now hooked on the point. “Ta-da! My best invention yet!”

“You invented the selfie stick,” Alex said. “I was wondering who to blame for that.”

“It’s a selfie sword, actually.” Heimdall wedged his face between Sam and Amir. “Say gamalost!” Gjallar flashed.

More fumbling as Heimdall retrieved his phone from the tip of his sword and inspected the picture. “Perfect!”

He proudly showed us the shot, as if we hadn’t been there when it was taken three seconds ago.

“Has anyone ever told you yo

u’re crazy?” Alex asked.

“Crazy fun!” Heimdall said. “Come on, check out some of these other shots.”

He gathered the four of us around his phablet and started flipping through his photo stream, though I was pretty distracted by how much Heimdall smelled like wet sheep.

He showed us a majestic picture of the Taj Mahal with Heimdall’s face looming large in the foreground. Then Valhalla’s dining hall, fuzzy and indistinct, with Heimdall’s total eclipse of a nose in perfect focus. Then the president of the United States giving a State of the Union address with Heimdall photo-bombing.

Pictures of all the Nine Worlds, all selfies.

“Wow,” I said. “Those are…consistent.”

“I don’t like my shirt in this picture.” He showed us a shot of elfish police beating a hulder with nightsticks, Heimdall grinning in front, wearing a blue striped polo. “But, oh, somewhere in here I’ve got this amazing photo of Asgard, with me making this angry face and pretending to eat Odin’s palace!”

“Heimdall,” Samirah interrupted, “those are really interesting, but we were hoping for your help.”

“Hmm? Oh, you want a picture with all five of us? Maybe with Asgard in the background? Sure!”

“Actually,” Sam said, “we’re looking for Thor’s hammer.”

All the excitement went out of Heimdall’s alabaster eyes. “Oh, not that again. I told Thor I couldn’t see anything. Every day he calls me, texts me, sends me unsolicited pictures of his goats. ‘Look harder! Look harder!’ I’m telling you, it’s nowhere. See for yourself.”

He flipped through more shots. “No hammer. No hammer. There’s me with Beyoncé, but no hammer. Hmm, I should probably make that my profile picture.”

“You know what?” Alex stretched. “I’m just going to lie down over here and not kill anybody annoying, okay?” He lay on his back on the Bifrost, stuck out his arms, and leisurely waved them through the light, making rainbow angels.

“Uh, yeah,” I said. “Heimdall, I know it’s a drag, but do you think you could take another look for us? We think Mjolnir is hidden underground, so—”

“Well, that would explain it! I can only see through solid rock for, like, a mile at most. If it’s deeper than that—”

“Right,” Sam jumped in. “The thing is, we kind of know who took it. A giant named Thrym.”

“Thrym!” Heimdall looked offended, as if that was someone he would never deign to take a selfie with. “That horrid, ugly—”

“He wants to marry Sam,” Amir said.

“But he won’t,” Sam said.

Heimdall leaned on his sword. “Well, now. That’s a dilemma. I can tell you where Thrym is easy enough. But he wouldn’t be stupid enough to keep the hammer in his fortress.”

“We know.” I figured we were close to the end of Heimdall’s attention span, but I told him about Loki’s nefarious wedding plans, the Skofnung Sword and Stone, the deadline of three more days, and Goat-Killer, who might or might not be on our side, telling us to find Heimdall and ask for directions. Every so often I randomly tossed in the word selfie to keep the god’s interest.

“Hmm,” said Heimdall. “In that case, I’d be happy to scan the Nine Worlds again and find this Goat-Killer person. Let me set up my selfie sword again.”

“Perhaps,” Amir suggested, “if you simply looked without using your phone?”

Heimdall stared at our mortal friend. Amir had said what we’d all been thinking, which was a pretty brave thing to do his first time in Norse outer space, but I was afraid Heimdall might decide to use his sword for something other than wide-angle shots.

Fortunately, Heimdall just patted Amir’s shoulder. “It’s all right, Amir. I know you’re confused about the Nine Worlds and whatnot. But I’m afraid you’re saying words that don’t make any sense.”

“Please, Heimdall,” Sam said. “I know it seems…strange, but gazing directly at the Nine Worlds might give you a fresh perspective.”

The god looked unconvinced. “Surely there’s another way to find your goat-killer. Maybe I could blow Gjallar and get the gods up here. We could ask