"Travel?" Dan said. "Where are we going?"

Amy glanced at the cop. She leaned closer to Dan and whispered, "First, we need to find a chaperone. And quickly.

Aunt Beatrice is going to call Social Services soon. We need to get home, get our stuff, and get out. If the police find out we've been disowned, they'll take us to a foster home or something. We'll never be able to find the thirty-nine clues."

Dan hadn't thought about this. He didn't know much about foster homes, but he figured he didn't want to live in one. Would a foster home let him take his collection?

Probably not.

"So how do we get an adult?" he asked. "Rent one?"

Amy twisted her hair into a noose. "We need somebody who'll let us do what we want without asking too many questions. Somebody old enough to look like we're being chaperoned, but not strict enough that they'll try to stop us. Somebody kind of pliable."

"Does 'pliable' mean we can lie to them?"

"Mrrp," Saladin said, like that sounded good to him as long as he got fresh fish.

The police car turned onto Melrose Street and pulled up in front of their weathered brownstone apartment building.

"This is the address?" the cop asked. She sounded bored and annoyed.

"Yes," Amy said. "I mean, yes, ma'am."

"You sure there's somebody home? Your guardian or whatever?"

"Nellie Gomez," Dan said. "She's our au pa -- "

His eyes widened. He looked at Amy, and he could tell she was thinking the same thing. It was so obvious even a Holt could've seen it.

"Nellie!" they said together. They got out of the police car with their cat and the jewelry box and raced up the front steps.

Nellie was just where Dan figured she'd be -- sacked out on the sofa with her earbuds in, bobbing her head to whatever weird music she was listening to while she punched text messages into her phone. A stack of cookbooks sat next to her on the couch. The top one read Exotic Mandarin Cuisine.

Dan let Saladin down to explore the apartment. Then he noticed the empty carton of Ben & Jerry's Cherry Garcia -- his Cherry Garcia -- sitting on the coffee table.

"Hey!" Dan protested. "That was mine!" Of course, Nellie didn't hear him. She kept jamming out and typing on her phone until Amy and Dan stood right over her.

Nellie frowned like she was annoyed she had to actually work. She pulled out one earbud. "Back already? Whoa -- what happened? You're all grungy."

"We need to talk," Amy said.

Nellie blinked, which was pretty cool to watch since her eyes were done in blue glitter eye shadow. She had a new nose ring shaped like a silver snake. Dan wondered why she wanted a snake curled inside her nostril.

"What do we need to talk about, kiddo?" she asked.

Amy looked like she wanted to hit Nellie with the jewelry box. Dan knew she hated it when Nellie called her kiddo, but she kept her voice polite.

"We -- we've got a deal for you. A new babysitting deal. It pays a lot of money."

Nellie pulled out her other earbud. They had her attention now. Three words always worked with Nellie: guys, food, and money.

She stood up. She was wearing her ripped British flag T-shirt, faded jeans, and pink plastic shoes. Her hair looked like a pile of wet straw -- half black, half blond.

She folded her arms and looked down at Amy. "Okay. What kind of deal?"

Dan was afraid Amy would freeze up, but she seemed to be keeping her nerves pretty well. Nellie wasn't as intimidating as some of the other au pairs they'd had.

"Urn ... it's a trip," Amy said. "You'd be our chaperone."

Nellie frowned. "Why isn't your aunt asking me about this?"

"Oh, she broke her neck," Dan blurted out.

Amy gave him a look like

Shut up!

"Broke her neck?" Nellie asked.

"It's not serious," Dan said. "Just a little break. She's, uh, going to be in the hospital for a while, though. So she figured we'd better take a trip. We talked to our Uncle Alistair. He said we'd need an adult to go with us."

That last part, at least, was true. Dan didn't know where he was going with this, but he plunged ahead. He figured if he could just keep Nellie confused, she couldn't call him a liar.

"It's this thing our family does," he said. "Kind of like a scavenger hunt. We visit a bunch of places and have fun."

"What sort of places?" Nellie asked.

"Oh, all kinds." Dan thought about the map in Grace's secret library -- all those pushpins. "That's part of the fun. We don't know all the places at the beginning. We could go all over the world."

Nellie's eyebrows shot up. "You mean, like, for free?"

Amy nodded, as if she were warming up to Dan's methods. "Yeah, it could take months! Traveling to exotic places where there's lots of ... um, food and guys. But you wouldn't need to be with us the whole time -- just for the adult stuff like buying airline tickets and checking into hotels and stuff. You'd have a lot of time on your own."

Yes, please, Dan thought. Nellie was okay, but the last thing he wanted was her following them around too closely.

"How are you going to pay for it?" Nellie said suspiciously.

Amy opened the jewelry box and dumped it on the table. The pearl bracelet, the diamond ring, and the emerald earrings glittered.

Nellie's mouth dropped open. "Oh -- my -- god. Did you steal that?"

"No!" Amy said. "It's from our grandmother! She wanted us to take this trip. She said so in her will."

Dan felt impressed. That wasn't exactly a lie, either.

Nellie stared at the jewelry. Then she picked up her phone and dialed.

Dan tensed. He had visions of Social Services -- whatever that was -- swooping in, guys with white coats and nets, maybe, taking them to a foster home.

"Hello?" Nellie said into the phone. "Yeah, Dad, listen, I've got a new job for the Cahills."

Pause.

"Yeah, it's really good money. So I can't make dinner tonight like I promised." Nellie picked up the diamond ring, but Amy snatched it away. "How long? Um ... we're traveling. So a few weeks. Maybe ... months?"

She yanked the phone away from her ear. On the other end, her dad was yelling in rapid Spanish.

"Dad!" Nellie said.

"No, claw. But the fall semester doesn't start for a month, and it's all, like, boring courses anyway.

I could just take more hours in the spring and -- "

Another burst of angry Spanish.

"Well, if you'd let me go to cooking school instead of stupid regular college -- "

Her dad's yelling got slightly louder than a nuclear explosion.

"Que, papa?"

Nellie yelled.

"Lo siento, you're breaking up. I'll call you when I get a better signal. Love ya!" She hung up.

"He's fine with it," she announced. "I'm in, kiddos."

On Amy's orders, Dan was only supposed to pack one bag. That meant clothes, but Dan wasn't interested in clothes. He looked around his room, trying to figure out what to take from his collections.

His bedroom was already way too small for his stuff. Against one wall were his tombstone rubbings. He'd have to roll them up or fold them to pack them, and that would ruin them. His closet was stacked with plastic bins holding his card collection and coin portfolios -- too many to choose from. Under his bed were boxes full of old Civil War weapons, his casts, his autographed celebrity photos, and a ton of other stuff.

He picked up his laptop, which he'd bought from the computer science teacher at school for $300. He'd have to take that, because he used it to find out stuff and make money. He knew the exact value of every trading card on the Internet. He'd learned to sell his duplicate cards at school and in the local card shops for a little more than he'd paid. It wasn't much, but he could make about $100 a month if he was lucky. And he was lucky. Unfortunately, he spent the money on rare stuff as fast as he made it.

He slipped the computer into his black duffel bag. Then he added three extra shirts, pants, underwear, a toothbrush, his inhaler, and -- finally -- his passport.

Their parents had gotten them passports right before they died, when Dan was four.

Dan didn't remember why. They'd never used them. Grace had insisted on renewing them last year, which had seemed kind of sil y to Dan at the time. Now he wondered....

He shoved the passport to the bottom of the bag. There was hardly any room left.

No way could he fit even a tenth of his stuff.

He dug under his mattress and brought out his photo album. It was a big white binder holding his most important collection: photos of his parents.

There was only one. It was burned around the edges: the only photograph that had survived the fire. His mom and dad were standing on the summit of a mountain with their arms around each other, smiling for the camera. They both wore Gortex parkas and thermal climbing pants, with harnesses around their waists. Instead of helmets, they wore baseball caps, so their eyes were hidden in shadows. His dad, Arthur, was tall and tan with salt-and-pepper hair and a nice smile. Dan wondered if he would look like that when he got older. His mom, Hope, had reddish-brown hair like Amy's. She was a little younger than their dad, and Dan thought she was very pretty. Her hat was an Orioles cap. His dad's was a Red Sox. Dan wondered if that was random, or if those were their favorite teams, and if they ever fought about which one was better. He didn't know. He didn't even know if they had green eyes like he did, because the caps hid their faces.

He wanted to collect other photos of them. He wanted to know where else they traveled and what they wore. He wanted to see a picture that had him in it. But there was nothing to collect. Everything from their old house had burned, and Grace always insisted she had no photographs of them, though Dan never understood why.

He stared at the photo and got a sinking feeling in the pit of his stomach. He thought about the fire at Grace's mansion, the man in black, Mr. McIntyre lying on the pavement, Uncle Alistair driving away like a madman, and his mom's handwriting in that Benjamin Franklin book.

What could be so important about a book? Dan knew the value of a lot of collectibles, but he'd never heard of anything worth burning down a house.

Grace must've known what she was doing, setting up this contest. She wouldn't have let him and Amy down. Dan told himself that over and over, trying to believe it.

There was a knock on his door. He took the plastic sleeve with the photograph out of the album and slipped it in his bag. He zipped it shut just as the door opened.

"Hey, dweeb," Amy said, but she didn't really sound mean. "You almost done?"

"Yeah. Yeah, I'm good."

She'd taken a shower and changed clothes -- back into her regular jeans and green T-shirt. She frowned at his full duffel bag, then looked at all the bins sitting in the closet. Dan guessed she could tell he hadn't sorted through them.

"You could, uh, take a backpack, too," she offered. "If that helps."

Coming from Amy, it was a pretty nice thing to say. But Dan stared at his closet.

Somehow he knew he wouldn't be coming back here ever again. "Amy, how much money do you think we'll get for the jewelry?"

Her hand went to her neck, and Dan realized she was wearing Grace's jade necklace.

"Um ... I don't know."