‘I’ve been in the foot tunnel,’ Kit said, as we approached Greenwich, where the dome of the tunnel entrance glowed in welcome. Used by thousands of pedestrians daily on this bridgeless stretch, it linked Greenwich on the south with Millwall on the north. ‘What about you, Jay, would you be able to go in that?’ He must have been thinking about our morning conversation about claustrophobia. I’ll say that for Kit: unlike many of his generation, he asked questions, he was interested in other people.

‘I’d be able to go in anything, I just might not like it.’ I had been in the Greenwich Foot Tunnel once, in fact, back in the day. As twentysomethings, a pack of us had raced through the long, narrow pipe, too competitive to be unnerved by the discovery of its being twice the distance it looked from the riverbank. ‘If it wasn’t too crowded, I’d know I’d be okay. I could run.’

‘What would you be running from?’ Kit asked.

‘Nothing. I’d just want to get back outside, above ground.’

He considered this. ‘The way I see it, it’s safer down there than up here.’

I glanced at him. ‘Why would you not be safe up here?’

He smirked. ‘Visibility, mate, know what I mean?’

I didn’t, and as he turned to his phone and began chuckling at something on Twitter, I found my thoughts trapped in the tubular worlds far below us. Running near the foot tunnel, much deeper, was the DLR between Cutty Sark and Island Gardens stations. It was all too easy for me to imagine the crush of people below us right now, held in a black tunnel at a red light, some rush-hour incident ahead having caused all moving stock to halt. Was sweat beading under layers of winter clothing as commuters grew uncomfortably conscious of being sealed in, the engines eerily still? Were they starting to ask themselves – or one another – What’s going on? Why aren’t we moving? Was there someone down there whose mind, like mine, spun faster, towards terror, someone thinking, When will the oxygen run out?

‘You all right?’ Kit peered at me, more curious than concerned. He lowered his phone. ‘You look like you’re having an allergic reaction to that beer.’

‘I’m fine. Fancy another one?’

‘Does the sun set in the west?’ But noticing how speedily we’d progressed – there were no signal failures on the water – he proposed we drop in at the Hope & Anchor instead, the nearest pub to St Mary’s Pier, situated on the river path leading east.

What with my nervous system having previously mistaken the Northern Line for the trenches of the Western Front, I had never before strolled into a pub at rush hour for anything other than a solo pulse-lowering double vodka and it was a thrill to submit to this commuter’s rite – or right, as Kit would have seen it. In spite of having lived in the area only half a year and been to the pub a fraction as frequently as I had, he was on first-name terms with the bar staff.

‘Nice spot in the summer,’ I told him as we took seats in the deep bay overhanging the water. ‘Did you know this is an old smugglers’ haunt?’

He lowered his pint. ‘What did they smuggle? Drugs?’

‘More likely wool. Because of high taxes. If you look in daylight, there’re gallows hanging over the water.’

‘Harsh.’ As the alcohol deepened his complexion, Kit turned mischievous. ‘So, Jamie, you ever done anything illegal?’

‘Like what?’

‘Y’know, the usual.’

‘I don’t know what your usual is, but I imagine the answer is yes. Hang on, you’re not recruiting me into some bomb-making cell, are you?’

‘Absolutely not.’ And he smashed our glasses together so hard I thought they might crack, letting out that machine-gun laughter that caused faces to turn towards us and soften at the sight of such bonhomie. ‘Clare seems up for a laugh, as well.’

‘Well, that was her New Year’s resolution. Trying new things. New people.’

‘Trying new people? I see.’ His eyebrows waggled. ‘Why aren’t you two married? I thought it was better for rich people to get married for inheritance tax reasons?’

‘We’re not the marrying kind.’ I didn’t point out that Clare was the rich one, not me, and it was obvious enough why: I wanted him to admire me. Envy me. To believe I had something he didn’t besides an archive of historical facts.

‘You don’t know how lucky you are, mate, being able to do whatever you like without worrying about bills. If that was me working in a café, I wouldn’t be able to pay my rent. I’d just be some loser.’

It was the same word he’d used to describe his father that morning. His face took on an expression I would come to know as peculiar to him: part co-conspirator, part tormentor. An oddly destabilizing kind of look. As he got to his feet to get another round in, I made a mental note never to make an enemy of Kit Roper.

5

27 December 2019

Under a luminous white sky, the river flickers silver, as if rebranded for the holiday. A riverboat appears from the east, sleek and low: Seymour. Henry’s third wife, queen for just a year. I can make out figures already queuing in the aisle to disembark at Westminster, eager to start a new shift making money for other people – or perhaps spending it on behalf of some government department. Stretching my throat, I raise my eyes and stare directly at the sun, dangerously pale behind dense cloud. I’m having one of those acute out-of-body rushes: This is really happening. This is really me with two detectives from the Met! I feel a sudden knifing of fear. Am I handling this okay? If I don’t act the right way, will I be arrested and put in a cell with a gangster or a paedophile?

‘All right, Jamie?’

I blink away the glare and pass a hand over my eyes. ‘I’m fine.’

Worrying perhaps that I’m losing concentration when we’ve scarcely begun, Merchison tasks Parry with fetching coffee, and as soon as we’re alone the atmosphere alters perceptibly. He’s like the teacher dismissing the bully to release me from my own face-saving survival instincts.

Now you can feel safe enough to tell the truth.

‘What rank are you?’ I ask him. ‘An inspector or something?’

But he’s a constable, like Parry, it turns out. This can’t be that important an investigation then, I think, heartened. ‘Look, whatever you seem to have decided about Kit and me, we’re not joined at the hip. Most weeks, I only see him on the boat.’

He rotates his pen, a miniature baton between his fingers. ‘So you’re not close friends, as Mrs Roper thinks?’

‘It depends how you define close.’ I wish I had a transcript of Melia’s interview. Knew what she’s revealed, what she’s chosen to draw a veil over. ‘We’ve socialized a bit at weekends as couples. Drinks, dinner, you know. And we sometimes have a drink on the boat after work.’

‘You carried on drinking on the boat on Monday, did you? Before this bust-up between you?’

‘We had one or two more for the road, yes.’

He taps the pen nib on his open pad, leaving little marks on the page. ‘Mr Callister and Ms Miles were with you, you said?’

‘Yes, though they both get off before us. Gretchen lives in Surrey Quays, and then Steve is on the Greenwich peninsula.’