‘I woke up at 8.36 a.m.’

He holds up a hand to stay her and offers up a reassuring smile. ‘Maybe not literally from the beginning. Perhaps from earlier that evening, say?’

‘Oh,’ she says, sounding surprised, ‘Well, OK then.’ She goes on to relate how she and Satnam had had an awkward conversation and Nevis had gone to the library only to return a few hours later and go straight to her room. At that point Satnam’s door was closed and there was no light on and Nevis assumed she was asleep. The phone call had come out of the blue.

‘If I hadn’t gone to the library…’

‘You mustn’t blame yourself,’ he says, then picking his way, adds, casually, ‘You say you had a difficult conversation?’

‘Yes, Satnam told me she wanted to leave Avon.’

Cullen’s pulse quickens. He blinks hard to try to steady himself. ‘Any idea why?’ he says, his voice hard and splintery.

She shakes her head and he hears himself breathe out heavily.

‘So no idea what might have precipitated this, then?’

‘Not really.’

He closes his eyes, drinking in the surge of freedom coursing through his body. Thank Christ, I’m in the clear. Nevis doesn’t know.

‘Good…’ He stops himself and rephrases, ‘I mean, naturally, you probably had other things on your mind.’

‘Yes.’

He observes her quietly for a moment or two as she sips her coffee.

‘And what’s on your mind now?’

She looks up, worried. ‘I’m scared it might happen again.’

He frowns. ‘Why would you think that?’

Nevis launches into a long explanation of suicide contagion most of which Cullen is already familiar with. He nods along and every so often interjects with, ‘I am aware,’ but the girl keeps on all the same. By the end Cullen is left wishing he’d never asked. The girl simply did not seem to realise that he no longer wanted to hear her rambling explanation. Absolutely no off button on her. Such an oddball.

‘We’re here to ensure the safety of all our students,’ he says blandly, smiling and doing his best to get her attention but he can see she has drifted off somewhere.

A few moments pass, then, suddenly looking up from her coffee, Nevis says, ‘I’m hoping to run some models. My aim is to determine the likelihood that another student might do something similar, based on the probability that the spread of suicide ideation – via various means of communication – increases as the number of suicides rises. I think I might be able to determine a threshold condition for a potential epidemic. Once I’ve got that, then the total probable size of an epidemic can be calculated. But it means I might be late with my coursework on deep vent modelling which is supposed to be handed in to Dr Ratner in…’ she checks her watch ‘…forty-five hours and twenty-seven minutes.’