She’s done nothing with the scrunched-up carrier bag and its contents, merely rolled it up and stuffed it behind the linen basket again.

Cate is supposed to be submitting a first draft of this latest manual to her publishers by the end of the month and she’s nowhere near ready. She sits at her laptop and words an email carefully, explaining that she will be late. She sighs as she presses send; being late is not something she makes a habit of. But she’s too distracted to rush it out; every time she looks at the screen her mind goes blank.

Instead she switches to her browser and googles ‘sex attacks NW3’. She opens a notepad and takes the cap off a biro.

The first attack in this spate now assumed to be have been carried out by the same balaclava-clad man was on 4 January, in Pond Street.

A young woman of twenty-two had her breasts roughly fondled at eleven thirty in the morning by a young man dressed in black who then escaped very quickly on a hired bicycle when someone approached.

She writes: ‘11.30 a.m., 4 January’.

The next attack was three days later. A sixty-year-old woman, who also had her breasts grabbed by a young man dressed in black. The attack had left her with bruises. It was at about four o’clock in the afternoon, near the leisure centre, near the school.

She writes it down.

The next was on 16 January. This was the one that she and Roan had read about in the papers. A Twenty-three-year-old woman grabbed from behind, sexually assaulted through her clothes; she never saw the man who attacked her but described him as smelling of laundry detergent and having small hands.

She writes that down too.

She knows the next two, both on roads very close to here. Both daytime. Both involving grabbing and bruising. And then the latest one, 24 February, at dusk, on the other side of the Finchley Road. Near the cinema. This one the most serious so far, a woman in hospital with injuries.

She breathes in hard and goes to her online calendar. Here she compares the dates and times with her own activities, desperately searching for something that does not correlate, for proof that nobody in this house could possibly be responsible for the terrible things that have been happening to women in the area.

She remembers the smell on Roan’s running clothes she’d found in Josh’s bedroom: not washing detergent at all, but sour, musky, ugly.

She thinks of the boys that Roan treats at his clinic, the boys not yet men who are already fantasising about hurting women.

She thinks of Josh, his hugs, his unknowability, his silence.

The shiver goes down her spine again.

But they are not Josh’s clothes, they are Roan’s clothes, and Roan too has his empty spaces. He is out all day and makes himself uncontactable. At night he runs in black Lycra; sometimes he runs for two hours, sometimes more. He comes back electrified and gleaming. He has secrets. Even if there wasn’t an affair last year, there was something. And there is the Valentine’s card from the child that is the wrong size for the envelope. And the missing girl who used to be his patient, who had been seen outside their house the night she disappeared.

There is so much. So much that is wrong. And now there is a bag full of foul-smelling Lycra. Now there is a balaclava.

But she cannot find a date that doesn’t correlate with either her husband or son being the attacker. On every single occasion her husband and her son might possibly have been out of the house.

She looks at the time. It’s nearly eleven. She imagines Josh at school, Roan at work. Those spaces. The cracks and the gaps where things can get in.

She picks up her phone and searches her contacts for Elona’s number, Tilly’s mum. She lets her finger hover over the call button for a moment, but loses her nerve. She presses the message icon instead and types a text. Dear Elona. Hope you and Tilly are both well. I just wanted to talk to you about something. Wondered if you were free for a coffee any time soon. Let me know!

Elona replies thirty seconds later. Sure. I’m free now if that’s any good?

They meet at the Caffè Nero on the Finchley Road. Elona is very groomed: black hair pulled back into a sculpted ponytail, a black cape with a fur trim, black jeans and high-heeled boots. Cate can’t understand how people can be bothered to be so glamorous. The effort, every day, the attention, the time, the money. Elona hugs her, enveloping her in a miasma of honey-sweet perfume.

‘It’s so lovely to see you, Cate,’ she says in her sing-song Kosovan accent. ‘You look well.’

‘Thank you,’ Cate says, although she knows she does not.

‘Let me get you a coffee. What would you like?’

Cate doesn’t have the energy to argue about who should be buying the coffee so she just smiles and says, ‘A small Americano please. With warm milk.’

She settles into an armchair and glances at her phone. There’s a message from Georgia. Mum?

Then another one: Mum. Can I make a cake tonight? Can you buy flour? And eggs?

Then two minutes later: And soft brown sugar. Love u.

Cate replies with a thumbs-up emoji and puts her phone away.

If anyone had told her a few years ago that one day Georgia would be the least of her problems, she would not have believed them.

Elona returns with an Americano for Cate and a mint tea for herself. ‘So,’ she says, ‘how’ve you been?’

‘Oh, God, you know,’ Cate begins. ‘All a bit high drama. As you may know?’

Elona nods effusively. ‘I heard, yes.’

It occurs to Cate that Elona probably cleared her diary in the thirty seconds after receiving Cate’s message.

‘So, what’s been going on?’ Elona asks.

‘Well, you know they’ve arrested the guy? The one who lives opposite us?’

‘Yes. I read that. Wow. And what do you think? Do you think it was him?’

‘Well, it certainly looks that way, doesn’t it? Though I read somewhere that it was him who told the police about seeing Saffyre there. Why would he have done that if he did it? If he hadn’t said anything, they’d never have known she was on our street. They’d never have looked in that building plot; they’d never have found her phone case and the blood. It all seems a bit strange.’

‘Unless he wanted to get caught?’

‘Well, yes, I guess that’s possible. But still, something doesn’t seem quite right to me.’

‘So, what’s your theory?’

Cate laughs nervously. ‘I don’t have one. I just have an anti-theory.’

Elona smiles, blankly, clearly hoping for more.

Cate changes the subject. ‘So, how’s Tilly. I haven’t seen her for quite a while.’

‘No,’ says Elona, her eyes dropping to the leaves in her tea. ‘No. She’s become a bit of a homebody. Doesn’t really like going out. Probably the weather. You know. The dark nights.’

‘When did this start?’ she asks. ‘The not going out?’

‘Gosh, I don’t know. A few weeks ago, I suppose. Since the New Year. She’s just …’ She pauses. ‘She just seems happier at home.’

‘Does it seem …?’ Cate begins and then pauses to find the right words. ‘Do you think maybe it had anything to do with that night? The night she was leaving ours. When she said the man had grabbed her.’

Elona looks up at Cate. ‘You know, the thought did occur to me.’

‘And?’

Elona shrugs. ‘She swears blind that nothing happened. That she made it up.’

‘It’s weird, though, isn’t it? The timing of it? And now it turns out that all the sex attacks in the area this year were kind of similar to what she originally said happened to her?’

‘They are?’

‘Yes. It was in the papers. Six since the New Year. All carried out by a young man in black. All involved rough grabbing and groping.’

Elona looks vaguely appalled.

‘I mean, can you see any reason why she might have taken back the claim? Maybe she was scared to go to the police?’

‘I honestly don’t know. I mean, we’ve barely spoken about it. I was so so cross with her for wasting everyone’s time like that, for lying. I was so embarrassed by her behaviour, you know, and I’m a single mum and everything she does feels like such a reflection on me, you know, and she thinks so highly of Georgia and of you and your family.’

‘She does?’

‘Yes. Oh God, yes. So much. She never had a real friend before Georgia. She’s in awe of her. And I think both of us were just a bit, you know, thrown by what happened that night.’

‘Oh, honestly, no! She must never worry what we think. Or what Georgia thinks. Georgia is rock solid. Nothing throws her. She’s really thick-skinned. You must tell Tilly that whatever it was that happened that night, whether it was real or not, she can tell Georgia. Georgia would never judge her. No one in our family would judge her. I promise.’

Elona smiles and puts her hand over Cate’s. She has a heavy gold chain around a narrow wrist; her nails are painted taupe. ‘Thank you, Cate,’ she says. ‘Thank you so much. I will talk to her tonight and see if there’s anything she’s not telling me. You’re very kind to take such an interest.’

Cate smiles tightly. She’s not being kind. She’s being desperate and scared.