Apparently I’m not the only one. A couple of girls with backpacks stroll down the aisle, their eyes dark and drowsy and seeming to say, We eat sex for breakfast. One of them smiles at Willem as she passes and says something in French. He replies, also in French, and helps her lift her bag into the overhead bin. The girls sit across the aisle, a row behind ours, and the shorter one says something, and they all laugh. I want to ask what was said, but all at once, I feel incredibly young and out of place, stuck at the children’s table for Thanksgiving.

If only I’d studied French in high school. I’d wanted to, at the start of ninth grade, but my parents had urged me to take Mandarin. “It’s going to be the Chinese century; you’ll be so much better able to compete if you speak the language,” Mom had said. Compete for what? I’d wondered. But I’ve studied Mandarin for the last four years and am due to continue next month when I start college.

I’m waiting for Willem to sit down, but instead he looks at me and then at the French girls, who, having deposited their things, are sashaying down the aisle.

“Trains make me hungry. And you never ate your sandwich,” he says. “I’ll go to the café for more provisions. What would you like, Lulu?”

Lulu would probably want something exotic. Chocolate-covered strawberries. Oysters. Allyson is more of a peanut-butter-sandwich girl. I don’t know what I’m hungry for.

“Whatever is fine.”

I watch him walk away. I pick up a magazine from the seat pocket and read a bunch of facts about the train: The Channel Tunnel is fifty kilometers long. It opened in 1994 and took six years to complete. The Eurostar’s top speeds are three hundred kilometers per hour, which is one hundred and eighty-six miles per hour. If I were still on the tour, this would be exactly the kind of Trivial-Pursuit fodder Ms. Foley would read to us from one of her printouts. I put the magazine away.

The train starts to move, though it’s so smooth that it’s only when I see the platform is pulling away from us, as though it’s moving, not the train, that I realize we’ve departed. I hear the horn blow. Out the window, the grand arches of St. Pancras glitter their farewell before we plunge into a tunnel. I look around the car. Everyone else seems happy and engaged: reading magazines or typing on laptops, texting, talking on their phones or to their seatmates. I peer over my seat back, but there is no sign of Willem. The French girls are still gone too.

I pick up the magazine again and read a restaurant review that I don’t absorb at all. More minutes tick by. The train is going faster now, arrogantly bypassing London’s ugly warehouses. The conductor announces the first stop, and an inspector comes through to take my ticket. “Anyone here?” he asks, gesturing to Willem’s empty seat.

“Yes.” Only his things aren’t there. There’s no evidence he ever was here.

I glance at my watch. It’s ten forty-three. Almost fifteen minutes since we left London. A few minutes later, we pull into Ebbsfleet, a sleek, modern station. A crowd of people get on. An older man with a briefcase stops next to Willem’s seat as if to sit there, but then he glances at his ticket again and keeps moving up the aisle. The train doors beep and then shut, and we are off again. The London cityscape gives way to green. In the distance, I see a castle. The train greedily gobbles up the landscape; I imagine it leaving a churned-up pile of earth in its wake. I grip the armrests, my nails digging in as if this were that first endlessly steep incline up one of those lunch-losing roller coasters that Melanie loves to drag me on. In spite of the blasting AC, a line of perspiration pearls along my brow.

Our train passes another oncoming train with a startling whoomp. I jump in my seat. After two seconds, the train is speeding past us. But I have the weirdest sensation that Willem is on it. Which is impossible. He would’ve had to fast-forward to another station to get that train.

But that’s not to say he’s on this train.

I look at my watch. It’s been twenty minutes since he went to the café car. Our train had not yet left the platform. He might’ve gotten off with those girls even before we departed. Or at this last station. Maybe that’s what they were saying. Why don’t you ditch that boring American girl and hang out with us?

He is not on this train.

The certainty hits me with that same whoomp as the oncoming train. He changed his mind. About Paris. About me.

Taking me to Paris was an impulse buy, like all those useless gadgets grocery stores put at the checkout aisle so you’re out the door before you realize what a piece of crap you just bought.

But then another thought hits me: What if this is all some sort of master plan? Find the most naïve American you can and lure her onto a train, then ditch her and send in the . . . I don’t know . . . the thugs to nab her? Mom DVR’d a segment about something just like this on 20/20. What if that’s why he was looking at me last night, that’s why he sought me out earlier today on the train from Stratford-upon-Avon? Could he have chosen easier prey? I’ve seen enough of those Animal Planet nature shows to know that the lions always go for the weakest gazelles.

And yet, as unrealistic as this possibility is, on a certain level, there’s a nugget of cold comfort in it. The world makes sense again. That at least would explain why I am on this train.

Something lands on my head, soft and crackly, but in my panic, it makes me jump.

And there’s another one. I pick up the projectile, a packet of Walker’s salt-and-vinegar crisps.

I look up. Willem has the guilty grin of a bank robber, not to mention loot spilling out of his hands: a candy bar, three cups of assorted hot beverages, a bottle of orange juice under one armpit, a can of Coke under the other. “Sorry about the wait. The café is at the other end of the train, and they wouldn’t open it until the train left St. Pancras, and there was already a queue. Then I wasn’t sure if you liked coffee or tea, so I got you both. But then I remembered your Coke from earlier, so I went back for that. And then on the way back, I stumbled onto a very cranky Belgian and spilled coffee all over myself, so I had to detour to the loo, but I think I just made things worse.” He plunks down two of the small cardboard cups and the can of soda on the tray table in front of me. He gestures to the front of his jeans, which now have a huge wet splodge down the front of them.

I am not the sort of person to laugh at fart jokes or gross-out humor. When Jonathan Spalicki let one rip in physiology last year and Mrs. Huberman had to let the hysterical class out early, she actually thanked me for being the only one to exhibit any self-control.

So it’s not like me to lose it. Over a wet spot.

And yet, when I open my mouth to inform Willem that I actually don’t like soda, that the Coke before was for Melanie’s hangover, what comes out is a yelp. And once I hear my own laughter, it sets off fireworks. I’m laughing so hard, I am gasping for air. The panicked tears that were threatening to spill out of my eyes now have a safe excuse to stream down my face.

Willem rolls his eyes and gives his jeans a yeah-yeah look. He grabs some of the napkins from the tray. “I didn’t think it was so bad.” He dabs at his jeans. “Does coffee leave a stain?”

This sends me into further paroxysms of laughter. Willem offers a wry, patient smile. He is big enough to accept the joke at his expense.

“I’m. Sorry.” I gasp. “Not. Laughing. At. Your. Pants.”

Pants! In her tutorial of British English versus American English, Ms. Foley had informed us that the English call underwear pants and pants trousers, and we should be mindful of announcing anything to do with pants to avoid any embarrassing misunderstandings. She went pink as she explained it.

I am doubled over now. When I manage to sit upright, I see one of the French girls coming back down the aisle. As she edges behind Willem, she rests a hand on his arm; it lingers there for a second. Then she says something in French, before slipping into her seat.

Willem doesn’t even look at her. Instead, he turns back to me. His dark eyes dangle question marks.

“I thought you got off the train.” The admission just slips out on the champagne bubbles of my relief.

Oh, my God. Did I actually say that? The giggles shock right out of me. I’m afraid to look at him. Because if he didn’t want to leave me on the train before, I’ve remedied that now.

I feel the give of the seat as Willem sits down, and when I gather up the courage to peer over at him, I’m surprised to find that he doesn’t look shocked or disgusted. He just has that amused private smile on his face.

He begins to unpack the junk food and pulls a bent baguette out of his backpack. After he’s laid everything out over the trays, he looks right at me. “And why would I get off the train?” he asks at last, his voice light and teasing.

I could make up a lie. Because he forgot something. Or because he realized he needed to get back to Holland after all, and there wasn’t time to tell me. Something ridiculous but less incriminating. But I don’t.

“Because you changed your mind.” I await his disgust, his shock, his pity, but he still looks amused, maybe a little intrigued now too. And I feel this unexpected rush, like I just took a hit of some drug, my own personal truth serum. So I tell him the rest. “But then for a brief minute, I thought maybe this was all some sort of scam and you were going to sell me into sex slavery or something.”

I look at him, wondering if I’ve pushed too far. But he is smiling as he strokes his chin. “How would I do that?” he asks.

“I don’t know. You’d have to make me pass out or something. What’s that stuff they use? Chloroform? They put it on a handkerchief and put up against your nose, and you fall asleep.”

“I think that’s just in movies. Probably easier for me to drug your drink like your friend suspected.”

“But you got me three drinks, one of them unopened.” I hold up the can of Coke. “I don’t drink Coke, by the way.”

“My plan is foiled then.” He exaggerates a sigh. “Too bad. I could get good money for you on the black market.”

“How much do you think I’m worth?” I ask, amazed at how quickly fear has become fodder.

He looks me up and looks me down, appraising me. “Well, it would depend on various factors.”

“Like what?”

“Age. How old are you?”

“Eighteen.”

He nods. “Measurements?”

“Five feet four. One hundred and fifteen pounds. I don’t know metric.”

“Any unusual body parts or scars or false limbs?”

“Does that matter?”

“Fetishists. They pay extra.”

“No, no prosthetic limbs or anything.” But then I remember my birthmark, which is ugly, almost like a scar, so I usually keep it hidden under my watch. But there’s something oddly tempting about exposing it, exposing me. So I slide my watch down. “I do have this.”

He takes it in, nodding his head. Then casually asks, “And are you a virgin?”

“Would that make me more or less valuable?”