‘Yup. A proper undercover surveillance operation.’ Charlie was tempted to take her voice to a falsely upbeat pitch: a defence against the frown lines she knew were etching themselves more deeply into Simon’s brow with each word she uttered. She resisted the temptation, and spoke normally. ‘We met for coffee in London. Liv suggested the venue: a place called Drink, Shop & Do – about fourteen footsteps from King’s Cross station. That’s not her neck of the woods and the café was everything she’d normally hate, so I had a feeling she’d be catching a train from King’s Cross after she’d said goodbye to me. I asked her if she was, and she denied it – said she’d chosen somewhere near King’s Cross because she knew that was where I’d be coming in to. Seemingly she’d forgotten she’d never done that ever before, even though I’ve been catching trains from Spilling to King’s Cross for many years—’

‘This isn’t doing you any good, Char,’ Simon cut in. ‘It’s become an obsession.’

‘Says the man who’s never been obsessed with uncovering the truth.’

‘That’s different. When it’s work—’

‘Liv’s my sister, Simon. I have to know, whatever it is. You used to feel the same way, remember? Last time I followed Liv to Cambridge, you were with me.’

‘Yeah. I also want to know, but … there’s a limit to how much prying you can and should do when it’s someone else’s private business. Let yourself be driven to extremes and the result can be catastrophic.’

‘Wow.’ Charlie giggled. ‘You’re a really … abstract, non-specific harbinger of doom, aren’t you? “Do a thing, and a thing might happen – scary scary!” Why the change of tune? This wasn’t your attitude at first. You know what I think? I reckon you assumed it’d be easier than it has been to find out the truth. We stalked Liv and Gibbs all the way to Cambridge – I thought that’d be enough, we’d definitely come back with the answer. But it wasn’t enough, and rather than risk more failure, you decided to pretend to respect their privacy.’

‘I felt like a prurient creep.’ Simon’s voice sounded thinned out. ‘Whatever they’re up to, it’s not our business.’

‘Right. So I shouldn’t tell you what happened when I followed Liv yesterday?’

Simon swore under his breath. ‘Tell me. Following her’s wrong, though. You can’t do that to someone you know. It’s not about her – I know she’s not being straight with us, but … it’s about how you want to behave, or it should be. The kind of person you want to be.’

‘Well, that’s easy.’ Charlie smiled to herself. ‘I want to be the kind of person who uses her cunning and ingenuity to find out the truth about her lying toe-rag of a sister. And – would you believe it? – that’s who I am!’

‘Tell me what happened.’

‘I like your extra-strict voice. Very sexy.’