She shifts on her seat and thinks back through the strange episodes of the last week. Ajay will be sympathetic. Scientific.

‘It was nothing,’ she says. She feels bad for wasting Ajay’s time, but she’d rather just confide in Bex for the moment.

Ajay senses her discomfort and gives her one of his chubby, reassuring smiles. She’s forgotten what a good bedside manner he has. He won’t rush her. He will bide his time until she’s ready to tell him.

‘He also said you’re making fantastic progress,’ he continues, beaming. ‘Thought you’d really turned a corner when he arrived last night.’

‘I’ve been feeling a lot better,’ she says, watching as Ajay removes a laptop from his attaché case and opens it on the table. He pulls out a headset similar to the one that Rob put on her earlier, also covered with electrodes.

‘He’s asked me to run some more recognition tests – try to establish whether the part of your brain that was damaged in the accident has fully recovered.’

‘Recognition tests? Sounds suspiciously like police work,’ Kate says. When she did her interview for the super-recogniser job with Wiltshire Police, she was shown inverted faces and altered images. There was also a ‘before they were famous’ test, in which she had to identify celebrities from poor-quality images taken when they were young.

Ajay smiles. He knows Kate never wants to work for the force again, but he agrees with Rob that her powers of recognition, almost non-existent after the accident, remain the best indicator of her brain’s overall recovery. The surgeon who operated on her talked of damage to her right temporal lobe, including the fusiform gyrus, the part of the brain that processes faces. He warned that facial blindness was a possibility. Kate was more worried about her ability to paint, particularly portraits of people.

‘We’re going to use the EEG headset to monitor a brainwave called a P3,’ Ajay says, checking his laptop.

‘What’s a P3?’

‘Electrical activity that occurs in the brain a fraction of a second after you recognise a face. The response spike is markedly stronger in super recognisers.’

‘Should I be flattered?’ Kate asks.

‘What’s interesting is that the reaction is involuntary – you can’t stop a P3 brainwave,’ he says. ‘It’s why they use it for lie detection.’

Ajay turns the laptop towards her and explains that she’s going to be shown two faces for five seconds each. She’ll then be shown hundreds of random facial images in quick succession, about ten per second, using a process called rapid serial visual presentation, or RSVP. Buried among them will be the two faces she was shown at the beginning. If her recognition skills are working, the deeper cognitive responses of her brain will trigger a P3 spike.

‘Are you ready?’ he asks.