We trudged down the steps. I was thinking how she smelled like a combination of old people’s house and bubble gum when she stopped so abruptly, I ran into her.

“Who’s that?” she asked.

I’d almost forgotten about the dude in the trench coat. He and my dad were standing across the street next to the big tree, having what looked like a serious argument. Dad’s back was turned so I couldn’t see his face, but he gestured with his hands like he does when he’s agitated. The other guy scowled and shook his head.

“Dunno,” I said. “He was there when we pulled up.”

“He looks familiar.” Sadie frowned like she was trying to remember. “Come on.”

“Dad wants us to wait in the cab,” I said, even though I knew it was no use. Sadie was already on the move.

Instead of going straight across the street, she dashed up the sidewalk for half a block, ducking behind cars, then crossed to the opposite side and crouched under a low stone wall. She started sneaking toward our dad. I didn’t have much choice but to follow her example, even though it made me feel kind of stupid.

“Six years in England,” I muttered, “and she thinks she’s James Bond.”

Sadie swatted me without looking back and kept creeping forward.

A couple more steps and we were right behind the big dead tree. I could hear my dad on the other side, saying, “—have to, Amos. You know it’s the right thing.”

“No,” said the other man, who must’ve been Amos. His voice was deep and even—very insistent. His accent was American. “If I don’t stop you, Julius, they will. The Per Ankh is shadowing you.”

Sadie turned to me and mouthed the words “Per what?”

I shook my head, just as mystified. “Let’s get out of here,” I whispered, because I figured we’d be spotted any minute and get in serious trouble. Sadie, of course, ignored me.

“They don’t know my plan,” my father was saying. “By the time they figure it out—”

“And the children?” Amos asked. The hairs stood up on the back of my neck. “What about them?”

“I’ve made arrangements to protect them,” my dad said. “Besides, if I don’t do this, we’re all in danger. Now, back off.”

“I can’t, Julius.”

“Then it’s a duel you want?” Dad’s tone turned deadly serious. “You never could beat me, Amos.”

I hadn’t seen my dad get violent since the Great Spatula Incident, and I wasn’t anxious to see a repeat of that, but the two men seemed to be edging toward a fight.

Before I could react, Sadie popped up and shouted, “Dad!”

He looked surprised when she tackle-hugged him, but not nearly as surprised as the other guy, Amos. He backed up so quickly, he tripped over his own trench coat.

He’d taken off his glasses. I couldn’t help thinking that Sadie was right. He did look familiar—like a very distant memory.

“I—I must be going,” he said. He straightened his fedora and lumbered down the road.

Our dad watched him go. He kept one arm protectively around Sadie and one hand inside the workbag slung over his shoulder. Finally, when Amos disappeared around the corner, Dad relaxed. He took his hand out of the bag and smiled at Sadie. “Hello, sweetheart.”

Sadie pushed away from him and crossed her arms. “Oh, now it’s sweetheart, is it? You’re late. Visitation Day’s nearly over! And what was that about? Who’s Amos, and what’s the Per Ankh?”

Dad stiffened. He glanced at me like he was wondering how much we’d overheard.

“It’s nothing,” he said, trying to sound upbeat. “I have a wonderful evening planned. Who’d like a private tour of the British Museum?”

Sadie slumped in the back of the taxi between Dad and me.

“I can’t believe it,” she grumbled. “One evening together, and you want to do research.”

Dad tried for a smile. “Sweetheart, it’ll be fun. The curator of the Egyptian collection personally invited—”

“Right, big surprise.” Sadie blew a strand of red-streaked hair out of her face. “Christmas Eve, and we’re going to see some moldy old relics from Egypt. Do you ever think about anything else?”

Dad didn’t get mad. He never gets mad at Sadie. He just stared out the window at the darkening sky and the rain.

“Yes,” he said quietly. “I do.”

Whenever Dad got quiet like that and stared off into nowhere, I knew he was thinking about our mom. The last few months, it had been happening a lot. I’d walk into our hotel room and find him with his cell phone in his hands, Mom’s picture smiling up at him from the screen—her hair tucked under a headscarf, her blue eyes startlingly bright against the desert backdrop.

Or we’d be at some dig site. I’d see Dad staring at the horizon, and I’d know he was remembering how he’d met her—two young scientists in the Valley of the Kings, on a dig to discover a lost tomb. Dad was an Egyptologist. Mom was an anthropologist looking for ancient DNA. He’d told me the story a thousand times.

Our taxi snaked its way along the banks of the Thames. Just past Waterloo Bridge, my dad tensed.

“Driver,” he said. “Stop here a moment.”

The cabbie pulled over on the Victoria Embankment.

“What is it, Dad?” I asked.

He got out of the cab like he hadn’t heard me. When Sadie and I joined him on the sidewalk, he was staring up at Cleopatra’s Needle.

In case you’ve never seen it: the Needle is an obelisk, not a needle, and it doesn’t have anything to do with Cleopatra. I guess the British just thought the name sounded cool when they brought it to London. It’s about seventy feet tall, which would’ve been really impressive back in Ancient Egypt, but on the Thames, with all the tall buildings around, it looks small and sad. You could drive right by it and not even realize you’d just passed something that was a thousand years older than the city of London.

“God.” Sadie walked around in a frustrated circle. “Do we have to stop for every monument?”

My dad stared at the top of the obelisk. “I had to see it again,” he murmured. “Where it happened...”

A freezing wind blew off the river. I wanted to get back in the cab, but my dad was really starting to worry me. I’d never seen him so distracted.

“What, Dad?” I asked. “What happened here?”

“The last place I saw her.”

Sadie stopped pacing. She scowled at me uncertainly, then back at Dad. “Hang on. Do you mean Mum?”

Dad brushed Sadie’s hair behind her ear, and she was so surprised, she didn’t even push him away.

I felt like the rain had frozen me solid. Mom’s death had always been a forbidden subject. I knew she’d died in an accident in London. I knew my grandparents blamed my dad. But no one would ever tell us the details. I’d given up asking my dad, partly because it made him so sad, partly because he absolutely refused to tell me anything. “When you’re older” was all he would say, which was the most frustrating response ever.

“You’re telling us she died here,” I said. “At Cleopatra’s Needle? What happened?”

He lowered his head.

“Dad!” Sadie protested. “I go past this every day, and you mean to say—all this time—and I didn’t even know?”

“Do you still have your cat?” Dad asked her, which seemed like a really stupid question.

“Of course I’ve still got the cat!” she said. “What does that have to do with anything?”

“And your amulet?”

Sadie’s hand went to her neck. When we were little, right before Sadie went to live with our grandparents, Dad had given us both Egyptian amulets. Mine was an Eye of Horus, which was a popular protection symbol in Ancient Egypt.

In fact my dad says the modern pharmacist’s symbol is a simplified version of the Eye of Horus, because medicine is supposed to protect you.

Anyway, I always wore my amulet under my shirt, but I figured Sadie would’ve lost hers or thrown it away.

To my surprise, she nodded. “’Course I have it, Dad, but don’t change the subject. Gran’s always going on about how you caused Mum’s death. That’s not true, is it?”

We waited. For once, Sadie and I wanted exactly the same thing—the truth.

“The night your mother died,” my father started, “here at the Needle—”

A sudden flash illuminated the embankment. I turned, half blind, and just for a moment I glimpsed two figures: a tall pale man with a forked beard and wearing cream-colored robes, and a coppery-skinned girl in dark blue robes and a headscarf—the kind of clothes I’d seen hundreds of times in Egypt. They were just standing there side by side, not twenty feet away, watching us. Then the light faded. The figures melted into a fuzzy afterimage. When my eyes readjusted to the darkness, they were gone.

“Um...” Sadie said nervously. “Did you just see that?”

“Get in the cab,” my dad said, pushing us toward the curb. “We’re out of time.”

From that point on, Dad clammed up.

“This isn’t the place to talk,” he said, glancing behind us. He’d promised the cabbie an extra ten pounds if he got us to the museum in under five minutes, and the cabbie was doing his best.

“Dad,” I tried, “those people at the river—”

“And the other bloke, Amos,” Sadie said. “Are they Egyptian police or something?”

“Look, both of you,” Dad said, “I’m going to need your help tonight. I know it’s hard, but you have to be patient. I’ll explain everything, I promise, after we get to the museum. I’m going to make everything right again.”

“What do you mean?” Sadie insisted. “Make what right?”

Dad’s expression was more than sad. It was almost guilty. With a chill, I thought about what Sadie had said: about our grandparents blaming him for Mom’s death. That couldn’t be what he was talking about, could it?

The cabbie swerved onto Great Russell Street and screeched to a halt in front of the museum’s main gates.

“Just follow my lead,” Dad told us. “When we meet the curator, act normal.”

I was thinking that Sadie never acted normal, but I decided not to say anything.

We climbed out of the cab. I got our luggage while Dad paid the driver with a big wad of cash. Then he did something strange. He threw a handful of small objects into the backseat—they looked like stones, but it was too dark for me to be sure. “Keep driving,” he told the cabbie. “Take us to Chelsea.”

That made no sense since we were already out of the cab, but the driver sped off. I glanced at Dad, then back at the cab, and before it turned the corner and disappeared in the dark, I caught a weird glimpse of three passengers in the backseat: a man and two kids.

I blinked. There was no way the cab could’ve picked up another fare so fast. “Dad—”