“What school did the other, older Thomas and Emily go to?”

“Thomas had just started at King’s College School in Cambridge when we last saw them. Emily was signed up to go there too.”

“Mum! Then that’s where we should be.”

“I thought about it.”

“And?”

“Why would Flora have been in Huntingdon doing chores on a school-day morning? She wouldn’t. If Thomas—new Thomas—is at King’s, she’d drop him off, then do those chores in Cambridge. Bank, post office, nipping to a shop . . . whatever. Why would she drive to Huntingdon?”

“Major logic fail,” says Zan. “She could have gone to Huntingdon for a million reasons. Maybe she’s got a friend who works there and they were meeting for lunch, or—”

“No. She was coming back to her car in the car park long before lunchtime.”

“Coffee, then.”

“It’s possible, but . . . I don’t know. I just figure: someone who’s in Huntingdon on a weekday morning is more likely to have a child here, at this school, than at a school in Cambridge. All other things being equal.”

“Yeah, but all other things about this situation are so not equal, are they? All other things are, like, totally fucked.”

“Zannah, stop swearing.” I turn to face her. “I mean it. You need to behave properly. Not only to please me and Dad, but because you want to go out into the world as—”

“Mum, stop trying to cram years of proper parenting into one little pep talk. You’re not a Mumsnet kind of mum, so don’t pretend you are.”

I don’t know what she means because I’ve never looked at Mumsnet. Actually, maybe that’s what she means.

“Do you want to come in with me?” I nod in the direction of the school.

“Sure—but to do what? No school’s going to answer questions about its pupils from someone who just walked in off the street.”

“Which is why we can’t ask questions. We have to pretend to know already. What’s tricky is working out what we’re going to pretend to know.”

“What do you mean?”

“Come on, let’s go. I’ve got an idea. Your job is to stand behind me and smile, looking like the respectable daughter of a respectable mum. And no swearing. First we need to grab something from the boot that might belong to a five-year-old boy.” My car’s boot operates as a kind of storage cupboard-cum-dustbin. There’s plenty in it to choose from.

Five minutes later, armed with a pale blue drawstring sports bag with a pair of socks inside it, Zannah and I are standing at the reception desk of Kimbolton Prep School. I press the buzzer and wait, rehearsing what I’m about to say.

A woman appears. She’s young and elegant, with short hair, a long slender neck and lovely earrings: small round pearls that look real, with solid silver flower shapes behind them. She reminds me of a swan, and looks friendly enough. “Can I help you?” she says.

“Yes, I hope so,” I say with a smile. “I’m a friend of Jeanette Cater’s. She left this in my car boot . . .”—I wave the bag in the air—“and I don’t have time to go to her house now and drop it off, so I thought . . . would it be okay to leave it with you?”

“Sure. No problem at all.”

I fight the urge to say, “So you know Jeanette Cater, then? Her son is here, at this school?”

The receptionist reaches for a pad and pen that are over on the other side of the desk. “Let me write down your details, just so I can tell Jeanette what happened.”

Shit.

“Beth Leeson,” says Zannah cheerfully, while I’m frantically trying to think of a fake name I can give. Too late now. “Oh—sorry, that’s my mum. She’s Beth Leeson. I’m Zannah.”

I try to look unflustered. Zan’s probably right: better not to lie. Besides, if the receptionist hands Jeanette Cater a random sports bag later and tells her it was brought in by a person whose name she doesn’t recognize and who claims to be her friend, it’s going to be pretty obvious who’s behind it—especially when Jeanette asks for a physical description of this mysterious woman. My hair is half brown and half blond at the moment; for months I’ve been too busy with clients and their problems—both physical and emotional—to get it sorted out.

Zan must have worked this out long before I did: I’ve been lied to, and I’m taking steps to find out why, and what’s really going on. I’m not ashamed of any of my actions and, by doing this, I’m letting Jeanette Cater know that I’m not.

It’s funny how quickly my thinking patterns have adjusted to all the unknowns. When I think about “Jeanette,” there’s a shadowy person in my mind who might be either Flora or the woman with the foreign accent. When I think about “Thomas and Emily,” sometimes they’re the two photogenic teenagers on Lewis’s Instagram and other times they’re the two small children I saw getting out of the silver Range Rover last Saturday.

The receptionist writes down “Beth Leeson.” “Phone number?” she asks me.

“Jeanette has my number.”

“Oh—ha, yes. Sorry! I’m so used to taking full details from people. Tell you what, though . . . if you could just let me have your number, just in case?”

Zannah recites our home number, and the receptionist writes it on the pad. When she looks up, I see uncertainty in her eyes. “And you’re Jeanette’s . . . friend?” she says, as if this is an outlandish concept.

“Yes.”

Two spots of red have appeared on her otherwise white cheeks. She holds out her hand awkwardly to take the sports bag from me. She’s gone from friendly and confident to nervous in the space of seconds. Why? “What’s your name?” I ask her.

“Lou Munday,” she says quickly. “Rhymes with the famous song, ‘Blue Monday’! Haha. My husband says that’s one of the reasons he married me.” She’s still on edge, but trying to hide it.

I pass her the bag.

We say our good-byes, and Zannah and I are halfway to the door when she calls after us, “Thanks again! I’ll give this to Jeanette later when she comes to collect Thomas.”

I freeze. Zannah and I exchange a look.

Thomas. Not Toby.

Kevin Cater lied. I now have proof, and it came from someone impartial, with no skin in the game. I should make a motivational sign like the one Lewis made for me, with “I trust myself” emblazoned across it, and stick it on the wall in my treatment room. My clients would love it. Lots of them are keen on positive psychology and mindfulness and things like that.

Zan is ahead of me, walking back to reception. “Did you say Toby, Mrs. Munday?” she asks in her fake-sweet voice, the one she only uses on me when she wants me to spend serious money on her. “Jeanette’s son isn’t called Toby. He’s called Thomas.”

“I know. I said Thomas.” She looks confused.

“And his sister’s not called Emma,” I say.

“No, she’s called Emily. I didn’t say anything about an Emma.” The red spots on her cheeks are growing.

“I know you didn’t. Can I tell you something that’s going to sound—”

“Mum,” says Zan curtly. She’s trying to warn me off.

“No, I’m doing this,” I say. “Mrs. Munday—”

“Please, call me Lou.”

“I don’t know how well you know the Cater family . . . for example, do you know that Thomas and Emily have a younger sister called Georgina? A baby?”

“We don’t know that’s true,” says Zannah.

Lou Munday looks mystified. She says, “The Caters don’t have a baby called Georgina, or any baby at all. They just have Thomas and Emily.”

“Just to check: we’re talking about Kevin and Jeanette Cater, who live at 16 Wyddial Lane, Hemingford Abbots?”

Lou has started to pluck at the skin of her neck with the fingers of her right hand. “I probably shouldn’t . . . I mean, I can’t. I can’t tell you where they live.”

“I’ve just told you where they live: 16 Wyddial Lane, Hemingford Abbots. Is that right?”

She starts to mumble about safeguarding issues. It’s been a while since she looked me in the eye.

“Does Jeanette Cater have a foreign accent?” Zannah asks her.

“A foreign . . . No, she . . . I’m sorry, but I’m afraid I can’t—”

“No? No foreign accent?”

“Zan, wait. Lou, I’m really sorry about this. I don’t want to make you feel uncomfortable, and obviously you don’t have to tell us anything else. We’ll leave in a minute, I promise. Before we go, though, I’d like to tell you something. Tell, not ask.”