Leo pulled a face. ‘Perhaps, before we get on to that delight, we should have a chat about the messages you allowed me to read.’

I braced myself for the ribbing I feared I was about to get.

‘The main things I noticed were that he’s got a good grasp of grammar, he’s very open to sharing his feelings, and he never once uses your name,’ he said, ticking the items off on his fingers, his tone matter of fact, to my relief.

‘The first two were things I liked about him. Call me a prissy pedant, but using “your” for “you are” is a bit of a turn off, to be honest.’

Leo let out a noise which I could only describe as a snigger.

‘Laugh all you like, but a girl’s got to set her boundaries.’

‘Duly noted. You do you.’

‘And he never uses my name? I hadn’t spotted that. I know it creeped me out when someone else contacted me and kept dropping my name into every other sentence. Take a look at this.’

I quickly opened the app on my phone and scrolled to find the message.

Hey Kat, you’re profile pic makes me want to know the secrets that are shining in you’re eyes. Do you like to snuggle like a cat, Kat? I bet I can make you purr, Kat.

Leo pretended to vomit. ‘Wow, that’s something else. What a creep. And extra negative points to him for his “your slash you’re” errors.’

‘Exactly, definite red flag right there.’ I gave an exaggerated shudder. ‘Is it any wonder that I was so open to Brian’s more sensitive– and grammatically correct– approach?’

‘Unfortunately, in Brian’s case, I think the lack of use of your name is a red flag for a different reason. It made me wonder if he’s been copying and pasting the same, apparently heartfelt, messages to all his marks.’

I shouldn’t have been surprised by this revelation, but it still hurt. I’d invested a lot of myself in my replies to Fake Brian, pouring thought into my answers to his questions, and genuinely caring about the ups and downs he detailed of his life. It was mortifying to imagine the shadowy fraudster getting a kick out of my innocent responses, gleefully anticipating his pay day. To my embarrassment, I felt tears pricking my eyes. I stared angrily at the path, willing myself to get it together. I was not going to waste any more emotional energy crying over past mistakes.

‘You’ve only got an hour for lunch, haven’t you? Perhaps we should move on to discussing whether or not I should join the site. I’m still not convinced it makes any sense,’ said Leo.

I was grateful for his tactful change of subject.

‘Well, as you’re being so funny about wanting to use my login details, it seems only sensible that you should have your own method of accessing the app.’ I decided to hold back on the other part of my plan, namely that we should take our investigation to the in-person events. It would be enough of a battle getting him to sign up to SO Ox. ‘Given Brian’s voice, I’m 90% certain that our target is male,’ I continued, ‘but if he has managed to play the system to set up multiple profiles, what’s to stop him pretending to be a woman and targeting the blokes too? I mean, he’d need to avoid the voice notes tactic, but you’ve seen his messages, I’m sure he could find other ways of being convincing.’

‘Hmm.’ Leo still sounded dubious.

‘What are you so afraid of?’

‘Did I say I was afraid? I’m not afraid at all. I just think it’s a waste of our time, but you’re the boss. Sign me up, if you insist.’

I smothered a smile at Leo’s defensiveness. ‘Okay, as you’re so relaxed about this, I’ll do the typing and you can concentrate on enjoying your sandwich. Hand your phone over.’

He looked like he was going to argue with me, but the appeal of food got the better of him and he reluctantly gave me his device before unwrapping the greaseproof cover of his pack-up.

‘Smells nice,’ I said, briefly distracted by the appealing aroma that emanated from his clearly home-made meal. The man obviously had skills. ‘What’s on the menu?’

‘Paws off, Fisher. You can get your own falafel and Mediterranean veg wrap.’

‘Mmm, fancy lunch. That sounds fal-afelly good.’ I couldn’t resist saying it.

‘If I was still in the police, I’d arrest you for crimes against the English language with that terrible pun. And, by the way, I want to see everything you type on that profile, and I reserve the right to veto the lot of it.’

‘You’re determined to be as difficult as possible about this, aren’t you? If I didn’t know better, I’d say you don’t trust me.’

‘Trust has to be earned,’ he said, in a holier-than-thou voice.

‘I prefer to think the best of people until proven otherwise,’ I said.

‘And how’s that working out for you?’