I recognize the brutish stone hulk of a Church of England church. They never lasted long for Mum: too much equivocation, too much compromise and the songs weren’t a patch on the Seventh-Day Adventists.

London gets heavier, more potent, as we walk and the buildings grow more sure of themselves. These are buildings that have been here for more than a hundred years; they’ve seen entire lifetimes come and go – they’ve earned their place in this world.

The people seem closer too, sparking and fizzing into existence as we walk. The basketball courts ring with the sound of bouncing balls and the heavy rumble of a bus causes Chiu to leap back in fright.

We reach Camden and the sound of people and shops and traffic snaps into focus. Pedestrians step crisply into view and then vanish, traffic cuts in and out of frame. The painted shopfronts. The tattoo parlours. The souvenir shops packed with London memorabilia. My heart thrums with it.

I catch a look from Farah.

“Pretty cool, huh?” she says.

“I wish we could see it for real,” I reply.

“What’s real? This is Camden, baby!” Something catches her eye and she grabs my arm playfully. “Hey, look – there’s a sign for the zoo. Shall we go?”

I laugh at first, thinking she’s not serious. But then I see it in her face.

“We need to get to UCL—” I say, guardedly.

“Oh, come on, we’ve got time for the zoo!” She widens her eyes. “I reckon elephants will be pretty wild here, I’ve always thought they’re more in this world than the ordinary world… They might talk in this world!”

I feel the mood shift as she senses my reluctance and reacts against it. Suddenly she’s filled with febrile energy.

“Chiu, you’d like to go to the ghost-zoo, wouldn’t you?” she says.

“I want to go to UCL,” Chiu says. “I want to go home—”

“Oh, oh and then we can go to the palace,” Farah continues, ignoring him. “We can take a dump in the queen’s toilet! We could—”

I stop walking and face her. “Farah, what’s going on?”

Her eyes flash angrily, the look she used to give teachers when one of them tried to tell her to quieten down. “Nothing,” she says. “We’re in London, Kyle, isn’t that what you always dreamed of? And we own this place. Look at it! Don’t tell me you’re not up for a bit of fun before we go back?”

“That wasn’t the plan,” I say.

“I’m changing the plan.”

Defiant. Dangerous.

“We don’t have time,” I say. “You’re sick.”

Wrong thing to say. I spot her resolve tighten. It was one thing to convince her to get up and leave the carpet shop, it’s another thing to convince her to walk away from all of London.

“You’re just scared,” she says.

“Farah, stop—” I say.

“No, you stop.” Suddenly she’s furious at me. “Stop hiding. That’s all you want to do. You want to hide away and do as you’re told.” She turns away from me. “If you’re going to be my boyfriend, Kyle, you’re going to have to up your game.”

My heart clenches. Chiu and I have to walk fast to keep up with her. She’s leading us down on to the canal towards the zoo.

The world whirls around me. We don’t have time for this. Farah is sick. Jonah is coming. He’s going to sniff us out. Our only hope is to get to UCL and get back before he catches up with us.

“Farah, wait—”

“Oh, Houses of Parliament,” she calls over her shoulder. “Then the zoo.”

I reach forward and snatch at her arm, stopping her, turning her towards me. She glares at me. “Let go of me,” she says.

I let go. We stare at each other. A silent stand-off with the smell of Camden – cigarettes and sweat and cheap perfume – fading in and out around us.

“Farah, UCL. That’s the brave move, you know it is.”

A hard, uncompromising look.

“Please, Farah,” Chiu adds, breaking our stalemate. “I want to go home.”

I see Farah’s eyes dart to him. He seems so young again. A child who misses his parents. Farah softens. She casts a regretful look towards the canal. “Fine,” she says, at last. “UCL first. But if it doesn’t work out, I’m taking a dump in the queen’s private bathroom.”

“UCL and then you can take a pretend dump wherever you like,” I concede.

“Promise?” Farah says.

“I promise.”

We press on, past Euston where the trains sound like monsters bellowing from below us and down towards Queens Square. There’s a special prehospital feeling I get when an appointment is coming up and I feel it now. Whatever was left of our optimism from last night has faded. I glance at Farah.

“You OK?” I ask.

“I don’t like hospitals,” she replies.

“Same.”

The roads are quieter here. The grand Georgian houses look as if they think they’re better than us because they outlast us so easily. We follow a gently curving crescent past a coffee shop and a bar that look deserted in this world. Then we’re standing in front of the unwelcoming facade of the building we’ve come all this way for. Five rows of big sash windows, sandy-coloured columns flanking a heavy wooden door and a sign:

UCL INSTITUTE OF COGNITIVE NEUROSCIENCE

“Have you ever been to this one before?” Farah says.

“No.”

We climb the couple of steps that lead up to the door and the black-and-orange sign. Farah and Chiu look at me expectantly and I wonder when they started treating me like the leader. I nod towards the door.

“Shall we?” I say.

“You first,” Chiu replies.

“This was your idea.”