Pierce’s eyes blaze, her jaw tightens. ‘You have been a DI for five minutes and yet you stand in judgement against those with several years’ more experience than you!’

‘I don’t mean any disrespect.’

‘I hope you can prove yourself, DI Archer.’

Archer holds her tongue. She knows she has already overstepped the mark.

‘You will report to me daily for the duration of this investigation. Is that understood?’

‘Yes, ma’am.’

‘I want to hear of every lead, every movement, every bit of progress. Or lack of. Is that understood?’

‘Of course, ma’am.’

‘I will be watching you, DI Archer.’

Pierce leaves and Archer lets out a breath that she hasn’t realised she’s been holding. Outside the incident room, the DCI stops to talk with Quinn. They both turn to look at Archer. Archer wonders if she can really trust the Irishman. They finish their conversation and Quinn approaches the incident room.

‘That looked tense,’ he says.

Archer shrugs. ‘We haven’t quite bonded yet.’

‘That much is evident. She’s asked me to show you to your office.’

The room in question is a ten-by-ten space next to Hicks’s office. Quinn opens the door and Archer’s nose wrinkles at the unaired musty odour inside. A blokey smell, like sweat, old meat and stale coffee, the footprint of hours fuelled by machine coffee and burritos from the local Chipotle.

‘Ugh . . . That’s rank!’ says Quinn.

A leather-topped desk inside littered with crumpled papers and tissues dominates the room. Underneath it she can see the source of the stench, a full wastepaper basket that the previous occupant didn’t bother to empty.

Sergeant Beattie appears. ‘Ma’am, PC Simpson is here.’

Archer looks beyond the sergeant and sees the large frame of the constable looking pale and terrified.

‘Thank you, Sergeant Beattie.’ She turns to Quinn. ‘Let’s talk to him in the incident room.’

Quinn escorts the constable inside.

‘PC Simpson, I am DI Grace Archer and I assume you know DS Quinn.’

Simpson flushes and nods.

‘Please sit down.’

The constable sits opposite Archer and starts talking before they can begin. ‘I should have checked, I know. I screwed up. I can’t believe it. It had been a long day and night. I had done a double shift and I was tired and just wanted to knock off. I’m really sorry. Shit! I can’t believe this happened to me. I’ve never screwed up like this . . .’

‘PC Simpson, take a breath,’ says Archer.

‘I’m sorry.’

‘Tell us what happened yesterday.’

‘I was driving around Trafalgar Square at the end of my shift and saw the van parked up on Charing Cross Road. I pulled over to see what they were up to. I thought it was harmless enough. They told me it was an exhibition for the Lord Mayor’s Show. I asked the bloke for the paperwork and he showed me a council approval letter.’