I walk to Fishmarket Close and when the fishwives see me there are questions and some relief, and I explain that I had to make an unexpected return to Edinburgh, but they should reassure Ma and Joan and Mr Munroe that I will be back soon, once all my business is complete. They give me a pair of haddock to take away with me and I take them to Aunt Jenever’s. ‘Fresh fish calls for a fry-up,’ the fishwives call.

Aunt Jenever’s shop is dark and quiet when I get there, but last night it shone like gold. I put the fish in the pantry and take a seat by the window. By and by, Cornelius drops in. Good Cornelius – Aunt Jenever’s boy who will do anything to keep the peace around here. Anything that needs doing.

‘There’s a nice bit of fish out the back for supper,’ I tell him. ‘I hope you’re sticking around that long.’

‘Not got much else to do,’ he says. ‘It’s been very quiet around here of late.’

Then there’s a bit of a swish and swirl of skirts, and a tippy-tap of pointy boots on the stairs, and we both fall silent, for down comes Mrs Rose, my pal Dorothy, looking radiant despite our late night out. She yawns and asks if there is any coffee.

‘It is a habit I have got into,’ she says, continuing to yawn. ‘A nice little cup of coffee when I wake up, although I usually wake much later than this. It is noisy in the mornings at this end of town. Greyfriars is more genteel, I dare say. And might there be somewhere I can get a tot of laudanum?’

I raise my eyebrows and Cornelius and I exchange glances. Cornelius has the shadow of a late night about his eyes.

‘Shall you be heading back to Greyfriars after your cup of coffee then?’ I ask Dorothy.

‘Perhaps, or I might stay here a while,’ she answers. ‘I feel quite safe here, you see.’

Cornelius stands up and goes to the kitchen to brew some coffee. Dorothy plays with the rings on her fingers and at last has the decency to look embarrassed at herself.

‘You did me a great favour last night,’ she says. ‘Dr McTavish had been a pest to me, begging me to do business with him again, but there was no way I’d consider it. I knew in my bones what he’d done to his wife. I would have left Edinburgh altogether, but the trade is so good here and the laudanum easy to get. I was worried he would do me a mischief one of these days, but I had no idea about the depths of his plot. Planning to keep me a prisoner – chained up.’ Her face is pinched.

‘He is no longer a threat to anyone,’ I tell her.

Cornelius comes back with three china cups filled with steaming coffee.