“And it’s so nice here?” she asks.

Ana Lucia and I have been together for three weeks. Christmas is in six weeks. You don’t need to be W to figure out the math on that one.

When I don’t answer, Ana Lucia says, “Or maybe you want me to go, so you can have someone else keep you warm?” Just like that, her tone changes, and the suspicion that I now realize has been lurking outside all along comes rushing in.

The next afternoon, when I head back to Bloemstraat, I find the boys at the table, papers sprawled out all over the place. Broodje looks up wearing the expression of a guilty dog who stole the dinner.

“I’m sorry,” he says straightaway.

“About what?” I ask.

“I may have told them a little bit about our conversation,” he stammers. “About what you said.”

“It wasn’t much of a surprise,” W says. “It was obvious something has been wrong since you came back. And I knew that scar wasn’t from a bicycle accident. It doesn’t look like something you’d get from a fall.”

“My story was I got hit by a tree branch.”

“But you got beaten up by skinheads,” Henk tells me. “The same ones the girl threw the book at the day before.”

“I think he knows what happened to him,” Broodje says.

“Crazy that you saw the same guys,” Henk says.

“More like bad luck,” Broodje says.

I don’t say anything

“We think you have that post-traumatic thing,” Henk says. “That’s why you’ve been so depressed.”

“So you’ve scrapped the celibacy theory?”

“Well, yeah,” Henk says. “Because you’re getting laid now and you’re still depressed.”

“You think it’s because of this,” I say, tapping the scar. “Not because of the girl?” I look at W. “You don’t think maybe Lien was right?”

The three of them try not to laugh. “What’s so funny?” I ask, feeling irritated and defensive all of a sudden.

“This girl didn’t break your heart,” W says. “She just broke your streak.”

“What’s that supposed to mean?” I ask.

“Willy, come on,” Broodje says, waving his arms to calm us all down. “I know you. I know how you are with girls. You fall in love and then it disappears like snow in the sun. If you’d had another few weeks with this girl you’d get tired of her, just like you do all the others. But you didn’t. It was almost like she dumped you. So you’re pining.”

You’re comparing love to a stain? Lulu had asked. She’d been skeptical at first.

Something that never comes off, no matter how much you might want it to. Yes, stain had seemed about right.

“Okay,” W says, clicking his pen. “Let’s start at the beginning, with as much detail as you can muster.”

“The beginning of what?”

“Your story.”

“Why?”

W starts explain about the Principle of Connectivity and how police use that to track down criminals, via who they associate with. He is always talking about theories like this. He believes that all of life boils down to mathematics, that there’s a numeric principal or algorithm to describe every event, even the random ones (chaos theory!). It takes me a while to understand that he means to use the Principle of Connectivity to solve the mystery of Lulu.

“Again, why? The mystery’s solved,” I snap. “I’m pining over the girl who got away, because she got away.” I’m not sure if I’m irritated because I think this is true or because I think it’s not.

W rolls his eyes, as if this is beside the point. “But you want to find her, don’t you?”

By that night, W has spreadsheets and graphs and on the mantel, below the fading Picasso poster, an empty poster board. “Principle of Connectivity. Basically, we track down the people we can find and see what connections they have back to your mystery girl,” W says. “Our best bet is to start with Céline. Lulu may have gone back for the suitcase.” He writes Céline’s name and draws a circle around it.

The thought has crossed my mind a number of times, and each time, I’ve been tempted to contact Céline. But then I think back to that night, the raw, wounded look on her face. In any case, it doesn’t matter. Either the suitcase is at the club, and Lulu hasn’t gone back for it, or it’s not there and she did somehow retrieve it and she found my notes inside and chose not to respond. Knowing does nothing to change the situation.

“Céline is off the table,” I say.

“But she’s the strongest connection,” W protests.

I don’t tell them about Céline and what happened at her flat that night, or what I promised her. “She’s out.”

W makes a rather dramatic X through Céline’s name. Then he draws a circle. Inside he writes, “barge.”

“What about it?” I ask.

“Did she fill out any paperwork?” W says. “Pay with a card?”

I shake my head. “She paid with a hundred dollar bill. She basically bribed Jacques.”

He writes “Jacques.” Circles it.

I shake my head again. “I spent more time with him than she did.”

“What do you know about him?”

“He’s a typical sailor. Lives on the water all year round. Sails in warm weather, kept the barge anchored in a marina, in Deauville he said, I think.”

W writes “Deauville” and puts a circle around it. “What about other passengers?”

“They were older. Danish. One married couple, one divorced couple that seemed married. They were all drunk off their heads.”

W writes “Drunk Danes” in a circle way off on the side of the poster board.

“We’ll consider them last resorts,” W says, moving to the next line. “I think the strongest lead is probably the most time-consuming.” Small grin there. Then on the bottom of the poster he writes “TOUR COMPANY” in large block letters.

“Only problem is I don’t know which one it was.”

“Odds are, it’s one of these seven,” W says, reaching for a computer printout.

“You found the tour company? Why didn’t you say so to begin with?”

“I didn’t find it. But I did narrow down the seven companies that do tours for American students that had a tour operating in Stratford-upon-Avon on the nights in question.”

“Nights in question,” Henk jokes. “This is starting to sound like a detective program.”

I stare at the printout. “How did you do that? In one night?”

I expect some complicated mathematical theorem, but he just shrugs and says: “The Internet.” He pauses. “There may be more than seven tours, but these are seven that I’ve confirmed as possibilities.”

“More?” Broodje says. “Seven already seems like lot.”

“There was a music festival that week,” I explain. It was why Guerrilla Will had gone to Stratford-upon-Avon in the first place. Tor generally avoided it; she had a poisonous grudge against the Royal Shakespeare Company, related to her even more toxic grudge against the Royal Academy of Dramatic Art, which had denied her admission twice. It was after that that she’d gone all anarchist and started Guerrilla Will.

W writes and circles the names of the tours on the poster: “Wide Horizons,” “Europe Unlimited,” “It’s a Small World,” “Adventure Edge,” “Go Away,” “Teen Tours!” and “Cool Europa.” “My guess is that your mystery girl was on one of these.”

“Okay, but there’s seven tours,” Henk says. “Now what?”

“I call them?” I guess.

“Exactly,” W says.

“Looking for . . . damn.” Once again, it comes back to me: I don’t even know her name.

“What identifying details do you know?” W asks.

I know the timbre of her laugh. I know the heat of her breath. I know the cast of moonlight against her skin.

“She was traveling with her friend,” I say, “who was blonde, and Lulu had black hair, cut short, in a bob, like Louise Brooks.” The boys all exchange a look. “She had a birthmark right here.” I touch my wrist. Since she first showed it to me on the train, I’d wondered what it would taste like. “She mostly kept it covered with a watch. Oh, right, she had an expensive gold watch. Or did have. I have it now.”

“That’s hers?” Broodje asks.

I nod.

W scribbles this down. “This is good,” W says. “The watch, especially. It identifies her.”

“Also, it gives you a cover,” Broodje says. “A reason to be tracking her down other than wanting to bone her a few more times to get her out of your system. You can say you want to return the watch.”

A half hour ago the poster board was empty, but now it’s half filled, all these circles, these tenuous connections, linking me to her. W turns toward it, too.

“Principle of Connectivity,” he says.

Over the next week, one by one, the circles on W’s connectivity board become Xs, as connections that I understand never actually existed are severed. It’s a Small World is for teens and their parents, so that one’s out. Go Away doesn’t have any record of anyone with a black bob and a watch on that tour. Adventure Edge refuses to divulge information about their clients and Cool Europa appears to have gone out of business. Teen Tours! doesn’t pick up the phone, though I’ve left several messages and emails.

It’s a dispiriting process, this. And complicated, too because I have to dodge time zones and callbacks and the ever-more-suspicious Ana Lucia. She’s not pleased with my more frequent absences, which I’ve attributed to the soccer league I’ve supposedly joined.

One night the phone rings past eleven. “Your girlfriend?” Ana Lucia says, her voice flat. Girlfriend is what she calls Broodje these days, because she thinks I spend more time with him than her. It’s a joke, but it gives my stomach a guilty twist every time.

I pick up the phone and cross to the other side of her room.

“Hi. I’m looking for a Willem de Ruiter?” The voice, in English, butchers the pronunciation of my name.

“Yes, hello,” I respond, trying to stay businesslike because Ana Lucia is right there.

“Hi Willem! This is Erica from Teen Tours! I’m responding to your email about trying to return a missing watch.”

“Oh, good,” I say, keeping it breezy, though Ana Lucia is now looking at me with narrowed suspicious eyes and I realize it’s because I’m speaking in English, and though I speak English with her, on the phone, with the boys, I always speak Dutch.

“We provide loss and theft insurance for all our travelers so if she’d lost something of value, there’d be a claim.”

“Oh,” I say.

“But I’ve checked all the claims for that time period, and all I’ve found is a claim for a stolen iPad from Rome and a bracelet that was recovered. But if you have a name, I can double check.”

I look at Ana Lucia, who’s decidedly not looking at me now, so I know she’s listening. “I can’t give you that now.”

“Oh. Okay. Well, maybe you can call me back with that later?”

“I can’t really do that either.”

“Oh. You sure it was a Teen Tours! tour?”

I now see how the missing-watch story is as cracked as the watch itself. Even if this was the right tour, there’s no way the tour operators would know Lulu lost the watch because she lost it after the tour. It’s a fiction. This is all a fiction. The truth is, I’m looking for a girl whose name I don’t know, who bears a passing resemblance to Louise Brooks. None of which I can say out loud. Nor do I want to. This is absurd.