‘Well, almost,’ said Cooper, thinking of Mark Roper and his preoccupation with clearing up after other people.

‘That makes me an accomplice,’ said Maggie. ‘I knew what she intended to do, and I helped her to do it. Technically, I’m guilty of conspiracy to cause an explosion.’

Neither of the police officers said anything. At that moment, it seemed the least of her concerns.

‘Ros had put petrol in two Evian water bottles. I don’t know who taught her how to do that. But then, I don’t know how she was brought up. I don’t even know who her adopted parents were. I don’t know anything about her at all, even though she was my daughter. I might have been able to put that right, in time. But they denied me the chance.’

‘Who do you mean by “they”?’

‘The men at the farm. The dog-fighting people. They killed Ros.’

‘Are you sure? Did you see it happen?’

‘I didn’t see it. I heard it.’

‘Tell us.’

‘Something must have gone wrong at the farm. I heard the first fire bomb go off, then the second, though it wasn’t as loud. But for some reason Ros didn’t get away as quickly as she meant to. The men came out of the shed with their dogs and they chased her back up the hill towards the tower. She was coming back to meet me, and I was supposed to keep her safe. But she never stood a chance. Oh, she might have been able to outrun the men, to escape among the trees in the darkness. But there were the dogs.’

‘If Ros never made it to the tower . . .’

‘I remember hearing the voices of the men shouting. And the dogs barking and snarling in the dark somewhere. I didn’t know what was happening, and I couldn’t see anything. Then there was a scream –’ Maggie stumbled to a halt. ‘The only other thing I remember is the man running at me out of the darkness, and then the knife and the pain . . .’ She looked at Tailby. ‘What actually happened to her? Can you tell me?’

‘Your daughter fell off Ringham Edge, very near the tower. She ran off the top of one of the Cat Stones trying to escape from the dogs.’

‘I see,’ said Maggie. She took a few seconds to digest the idea, as if trying to fit it in with her mental picture. ‘It’s ironic, isn’t it? It was all because of the dogs. It was the dogs that she was trying to save.’

‘I’m afraid those particular dogs were trained to kill,’ said Tailby. ‘We seized six pit bull terriers from various addresses when we made our arrests. Now they will have to be destroyed anyway.’