‘As you know, hair grows around a centimetre every thirty days, and the sample from Penny has been analysed for the last ninety days. I’ve made a note of all the possible effects of each drug, and I’ve also looked into where she might have bought them. A couple of them could have come through legitimate prescriptions, although they’re also available on the street – or online of course – so that’s inconclusive. But when we look at the sequence, it raises a few questions about her state of mind.’

Tom had already indicated to Philippa that the mixture of drugs would have conflicting impacts on the mind, so he was keen to hear what Lynsey had to say, but through the open door he heard the squeak of rubber on vinyl flooring that indicated the arrival of Becky, who had taken to wearing trainers around the office as she had grown larger. And they were moving at a faster than normal pace.

‘Hold that thought, Lynsey. If Becky’s moving that quickly, something must be up.’

Becky’s face appeared around the door, beaming from ear to ear.

‘We’ve got her! We know who Penny is.’

Tom and Lynsey followed Becky back to the incident room, where Keith was pinning photographs on the board. He turned as Tom entered the room, his back straightening ever so slightly. Even after all these months working in the team, he seemed to find it necessary to stand to attention when a senior officer walked into the room.

‘Okay, Keith, what have we got?’

‘We’ve been looking into the girl who tried and failed to kill herself at the Flash – the one who was rescued from the water but who subsequently succeeded in committing suicide elsewhere. She was Esme DuPont. Her twin was Jasmine, more commonly known as Jaz.’

Tom was hit by conflicting emotions: relief at the possibility that they knew who their victim was, and dismay at the thought that Keith was about to tell him their Penny – now dead – had been Esme’s surviving twin, Jasmine. How horrific for both sisters to die so young.

‘We managed to get photos of the girls. It’s only just over two years since Esme committed suicide, and the twins were both Facebook users. A lot of their pictures are of the two of them together.’