‘One of our detectives, a rather incensed fellow called Carl Hoskins, has been through the kitchen waste bin,’ Gillard said. ‘But identifying disposable paper plates from all the other rubbish has been a bit beyond him.’

After the call was finished, Sam looked up from her book. ‘Craig, wasn’t there that case years ago of some European winemakers putting antifreeze in their wine to make it sweeter?’

Gillard nodded. ‘I vaguely recall that. I suppose it must’ve been very low quantities, I don’t remember anyone being killed.’

‘It is weird,’ Sam said. ‘Mrs Roy got poisoned by one thing, and Colin Hodges by another. Who could possibly have got them both?’

‘I can’t imagine,’ Gillard said. ‘But let’s assume it was the cake, then it must’ve been Kirsty Mockett. And for some reason she was trying to kill me.’

‘You?’

‘Yes – Colin only died because he ate my slice as well as his own, after I had to leave the meeting early.’

‘I don’t know what you’re talking about.’

Kirsty Mockett was sitting in an interview room opposite DCI Gillard and DC Hoskins. ‘There is nothing wrong with my cake. There were no allergens in it, I’m always very careful.’ The young CSI trainee, casually dressed in jeans and a sweatshirt and fresh back from her weekend in the New Forest, looked in a state of shock.

‘It wasn’t an allergic reaction,’ Hoskins said. ‘This was something that had no place in any food.’

Kirsty had already described the process she had gone through to make the cake and the ingredients she had used.

‘If it was the cake wouldn’t you all have been sick? And so would I. I mean, is anybody else unwell?’

‘It is possible to poison a single slice,’ Hoskins said accusingly.

‘What, you mean like the old hag with the apple in Snow White?’ she rolled her eyes. ‘I don’t believe this.’

‘Where was the cake stored after you brought it in to work?’ Gillard asked.

‘In the refrigerator in the kitchenette outside the training room.’

‘So somebody could have interfered with it,’ he continued.

‘Well, possibly. But nobody except my other trainees and Rob knew it was my birthday. And who were they intending to kill, given that they couldn’t have known who was going to get which bit? I mean it’s just ridiculous.’

Hoskins leaned forward and stabbed a finger towards her. ‘Ms Mockett, a serving police officer, my friend, has died shortly after eating a slice of your cake. I wouldn’t say anything about that is ridiculous. I’m not getting any sense of contrition here.’

‘I’m horrified that the man is dead, of course I am. But contrition is for those who are responsible. And I’m not responsible.’

Gillard felt quite uncomfortable about the belligerency of Hoskins’ questioning. ‘Kirsty, we are just struggling to find out how a lethal dose of poison came to find its way into his system.’

‘But what poison? Not thallium again?’

‘As you are a suspect we are not at liberty to tell you,’ Hoskins said, with a triumphant curl of his lip. Kirsty looked like she was about to burst into tears.