'Jack would never have Botox!' I say. 'Or a face-lift!'

'You don't know that!' She gives me a telling look. 'Compare a recent photo of Jack with an old one, and I bet you see a difference—'

'OK, Miss Marple,' says Lissy, rolling her eyes. 'So what are your other seven theories?'

'Let me see …' Jemima turns the page of her notebook. 'OK, this one's rather good He's in the Mafia.' She pauses for effect. 'His father was shot, and he's planning to murder the heads of all the other families.'

'Jemima, that's The Godfather,' says Lissy.

'Oh.' She looks put out. 'I thought it seemed a bit familiar.' She crosses it out. 'Well, here's another one. He has an autistic brother …'

'Rain Man.'

'Oh. Damn.' She pulls a face and looks at her list again. 'So maybe not that after all … or that …' She start crossing entries out. 'OK. But I do have one more.' She raises her head. 'He's got another woman.'

I stare at her, feeling a jolt. Another woman. I never even thought of that.

'That was my last theory, too,' says Lissy apologetically. 'Another woman.'

'You both think it's another woman?' I look from face to face. 'But … but why?'

Suddenly I feel really small. And stupid. Has Jack been playing me along? Have I been even more naïve than I originally thought?

'It just seems quite a likely explanation,' says Jemima with a shrug. 'He's having some clandestine affair with a woman in Scotland. He was paying her a secret visit when he met you. She keeps phoning him, maybe they were having a row, then she comes to London unexpectedly, so he has to dash off from your date.'

Lissy glances at my stricken face.

'But maybe he's relocating the company,' she says encouragingly. 'Or a fraudster.'

'Well, I don't care what he's doing,' I say, my face burning. 'It's his business. And he's welcome to it.'

I get a pint of milk from the fridge and slam it shut, my hands trembling slightly. Sensitive and complicated. Is that code for 'I'm seeing someone else?'

Well, fine. Let him have another woman. I don't care.

'It's your business too!' says Jemima. 'If you're going to get revenge—'

Oh for God's sake.

'I don't want to get revenge, OK?' I say, turning round to face her. 'It's not healthy. I want to … heal my wounds and move on.'

'Yes, and shall I tell you another word for revenge?' she retorts, as though pulling a rabbit out of a hat. 'Closure!'

'Jemima, closure and revenge are not actually the same thing,' says Lissy.

'In my book they are.' She gives me an impressive look. 'Emma, you're my friend, and I'm not going to let you just sit back and allow yourself to be mistreated by some bastard man. He deserves to pay. He deserves to be punished!'

I stare at Jemima, feeling a few tiny qualms.

'Jemima, you're not actually going to do anything about this.'

'Of course I am,' she says. 'I'm not going to stand by and see you suffer. It's called the sisterhood, Emma!'

Oh my God. I have visions of Jemima rooting through Jack's rubbish bins in her pink Gucci suit. Or scraping his car with a nail file.

'Jemima … don't do anything,' I say in alarm. 'Please. I don't want you to.'

'You think you don't. But you'll thank me later—'

'No I won't! Jemima, you have to promise me you're not going to do anything stupid.'

She tightens her jaw mutinously.

'Promise!'

'OK,' says Jemima at last, rolling her eyes. 'I promise.'

'She's crossing her fingers behind her back,' observes Lissy.

'What?' I stare at Jemima in disbelief. 'Promise properly! Swear on something you really love.'

'Oh God,' says Jemima sulkily. 'All right, you win. I swear on my Miu Miu ponyskin bag, I won't do anything. But you're making a big mistake, you know.'

She saunters out of the room, and I watch her, a bit uneasily.

'That girl is a total psychopath,' says Lissy, sinking down onto a chair. 'Why did we ever let her move in here?' She takes a sip of tea. 'Actually, I remember why. It was because her dad gave us a whole year's rent in advance—' She catches my expression. 'Are you OK?'

'You don't think she'll actually do anything to Jack, do you?'

'Of course not,' says Lissy reassuringly. 'She's all talk. She'll probably bump into one of her ditzy friends and forget all about it.'

'You're right.' I give myself a little shake. 'You're right.' I pick up my cup and look at it silently for a few moments. 'Lissy, do you really think Jack's secret is another woman?'

Lissy opens her mouth.

'Anyway, I don't care,' I add defiantly, before she can answer. 'I don't care what it is.'

'Sure,' says Lissy, and gives me a sympathetic smile.

As I arrive at the office, Artemis looks up from her desk with a bright-eyed glance.

'Morning Emma!' She smirks at Catherine. 'Read any intellectual books lately?'

Oh, ha ha-di-ha. So, so funny. Everyone else at work has got bored with teasing me. Only Artemis still thinks it's completely hilarious.

'Actually, Artemis, I have,' I say brightly, taking off my jacket. 'I read this really good book recently, it was called "What to do if your colleague is an obnoxious cow who picks her nose when she thinks no-one's looking."'

There's a guffaw around the office, and Artemis flushes a dark red.

'I don't!' she snaps.

'I never said you did,' I reply innocently, and switch on my computer with a flourish.

'Ready to go to the meeting, Artemis?' says Paul, coming out of his office with his briefcase and a magazine in his hand. 'And by the way, Nick,' he adds ominously, 'Before I go, would you mind telling me what on earth possessed you to put a coupon ad for Panther Bars in —' he consults the front cover

'— Bowling Monthly magazine? I'm assuming it was you, as this is your product?'

My heart gives a little swoop, and I lift my head. Shit. Double shit. I didn't think Paul would ever find out about that.

Nick shoots me a dirty look and I pull an agonized face back.

'Well,' he begins truculently. 'Yes, Paul. Panther Bars are my product. But as it happens—'

Oh God. I can't let him take the blame.

'Paul,' I say in a trembling voice, half raising my hand. 'Actually, it was—'

'Because I want to tell you,' Paul grins at Nick. 'It was bloody inspired! I've just had the feedback figures, and bearing in mind the pitiful circulation … they're extraordinary!'

I stare at him in astonishment. The ad worked?

'Really?' says Nick, obviously trying to sound not too amazed. 'I mean — excellent!'

'What the fuck compelled you to advertise a teenage bar to a load of old codgers?'

'Well!' Nick adjusts his cufflinks, not looking anywhere near me. 'Obviously it was a bit of a gamble. But I simply felt that maybe it was time to … to fly a few kites … experiment with a new demographic …'

Hang on a minute. What's he saying?

'Well, your experiment paid off.' Paul gives Nick an approving look. 'And very interestingly, it coincides with some Scandinavian market research we've just had in. If you'd like to see me later, to discuss it—'

'Sure!' says Nick with a pleased smile. 'What sort of time?'

No! How can he? He is such a bastard.

'Wait!' To my own astonishment, I leap to my feet in outrage. 'Wait a minute! That was my idea!'

'What?' Paul frowns.

'The Bowling Monthly ad. It was my idea. Wasn't it, Nick?' I look directly at him.

'Maybe we discussed it,' he says, not meeting my eye. 'I don't really remember. But you know, something you'll have to learn, Emma, is that marketing's all about team-work …'.

'Don't patronize me! This wasn't team-work. It was totally my idea. I put it in for my grandpa!'

Damn. I didn't quite mean to let that slip out.

'First your parents. Now your grandpa,' says Paul, turning to look at me. 'Emma, remind me, is this Bring Your Entire Family To Work week?'

'No! It's just …' I begin, a little hot under his gaze. 'You said you were going to axe Panther Bars, so I … I thought I'd give him and his friends some money off, and they could all stock up. I tried to tell you at that big meeting, my grandfather loves Panther Bars! And so do all his friends. If you ask me, you should be marketing Panther Bars at them, not teenagers.'

There's silence. Paul looks astonished.

'You know, in Scandinavia, they're coming to the same conclusion,' he says. 'That's what this new research shows.'

'Oh,' I say. 'Well … there you go.'

'So why does this older generation like Panther Bars so much, Emma? Do you know?' He sounds genuinely fascinated.

'Yes, of course I know.'

'It's the grey pound,' puts in Nick wisely. 'Demographic shifts in the pensionable population are accounting for—'

'No it's not!' I say impatiently. 'It's because … because …' Oh God, Grandpa will absolutely kill me for saying this. 'It's because … they don't pull out their false teeth.'

There's a staggered pause. Then Paul throws back his head and roars with laughter. 'False teeth,' he says, wiping his eyes. 'That is sheer bloody genius, Emma. False teeth!'

He chuckles again and I stare back at him, feeling the blood beating in my head. I've got the strangest feeling. Like something's building up inside me, as though I'm about to—

'So can I have a promotion?'

'What?' Paul looks up.

Did I really just say that? Out loud?

'Can I have a promotion?' My voice is trembling slightly, but I hold firm. 'You said if I created my own opportunities I could have a promotion. That's what you said. Isn't this creating my own opportunities?'