The faster she ran the more terrified she became until she finally broke through the trees sobbing and petrified, and alone.

Even today, as she leaned in to the mirror, she could see the tiny scars made by the trees and her own terror. And she remembered that night she’d left her best friend to be taken instead of her. Of course, the friend had burst through the trees a moment later, also sobbing. And they both knew that dead boy had indeed stolen something. He’d stolen the trust between friends.

Sharon Harris believed houses could be haunted, but she knew for sure people were.

‘Do I believe in haunted houses, Chief Inspector? Are you really asking me that? A doctor and a scientist?’

‘I am,’ he smiled.

‘Do you believe it?’

‘Now, you know me, doctor. I believe everything.’

She hesitated for a moment, then decided, what the hell.

‘That place is haunted.’ She didn’t have to look, they both knew what she meant. ‘By what, I don’t know. Madeleine Favreau knows, but she had to die to find out. Me? I don’t want to know that badly.’

The two sat quietly on the bench in the very center of the peaceful village. Around them, as they talked about ghosts and demons and death, people walked their dogs and chatted and gardened. Gamache waited for Dr Harris to continue, and watched as Ruth tried to coax the tiny balls of fluff into the pond.

‘I did a bit of research this afternoon on ephedra. It’s from the’ – she pulled a notepad from her pocket – ‘gymnosperm shrub.’

‘It’s an herb, isn’t it?’ said Gamache.

‘You knew?’

‘Agent Lemieux told me.’

‘It grows all over the place. It’s an old-fashioned cold remedy and antihistamine. The Chinese knew about it centuries ago. Called it Ma Huang. Then the pharmaceuticals got hold of it and started making Ephedrine.’

‘You say it grows all over the place—’

‘You’re wondering whether it grows here? It does. There’s one over there.’ She pointed to a huge tree on a front lawn. Gamache got up and walked over to it, bending down to pick up a leathery, brown leaf, fallen in the autumn.

‘It’s a ginkgo tree,’ said Dr Harris, joining him and picking up a leaf of her own. It was an unusual shape, more of a fan than a classic leaf, with thick veins, like sinews. ‘It’s part of the gymnosperm family.’

‘Could someone extract ephedra from this?’ Gamache showed her his leaf.

‘I don’t know whether it comes from the leaf or the bark or something else. What I do know is that being from the same family doesn’t necessarily mean it has ephedra in it. But as I said before, the combination of ephedra and a scare wasn’t enough.’

They turned and walked back to the bench, Gamache rubbing the leaf between his fingers, feeling its skeleton in his hand.

‘Something else had to happen?’ he asked.

‘Something else had to exist,’ Dr Harris nodded.

‘What?’ Gamache asked, hoping she wasn’t going to say a ghost.

‘Madeleine Favreau had to have had a heart condition.’

‘Did she?’

‘She did,’ said Dr Harris. ‘According to my autopsy, she had fairly severe heart damage, almost certainly from her breast cancer.’

‘Breast cancer damages the heart?’

‘Not the cancer, but the treatment. The chemo. Breast cancer in younger women can be extremely aggressive so doctors give high doses of chemo to fight it. The women are normally consulted before it’s done, but the equation is simple. Feel wretched for months, lose your hair, risk a heart problem or almost certainly die of breast cancer.’

‘Jesus wept,’ whispered Gamache.

‘I think so.’

‘You’re looking very serious.’ Ruth Zardo had walked up to their bench. ‘Fucking up the Favreau case?’

‘Probably.’ Gamache rose and bowed to the old poet. ‘Do you know Dr Harris?’

‘Never met.’ They shook hands. This was about the tenth time Sharon Harris had been introduced to Ruth.

‘We’ve been admiring your family.’ Gamache nodded toward the pond.

‘Do they have names?’ Dr Harris asked.

‘The big one’s Rosa and the little one’s Lilium. They were found among the flowers by the pond.’

‘Beautiful,’ said Dr Harris, watching Rosa plop into the pond. Lilium took a step and stumbled. Ruth, her back to the birds, somehow sensed something was wrong and limped rapidly to the pond, lifting the little one out, soaking but alive.