‘I hope this pie is safe,’ my father said, judiciously cutting it into two equal pieces.

‘Safe? Joan will have bought it from Goodman Quiller. His meat is clean, if sometimes a little tough.’

‘I am thinking of the sickness. If the bloody flux has spread to the butchers, the meat may be contaminated.’

I cast a wary glance at my piece of pie. Butcher Quiller’s wife had a light hand with pastry – her pastry put Joan’s to shame – and the meat looked fine grained and free of gristle. A quivering golden jacket of clear jelly encased the meat inside the pastry. My stomach groaned with hunger. Even the soup had barely taken the edge off it. I poked the pie tentatively with the tip of my knife.

‘Do you think it is safe?’

‘Don’t worry.’ He smiled at me. ‘There’s been no sign of illness yet amongst the butchers. I am going to eat mine.’

With that he set to, and I ate my own share greedily. Afterwards we worked at renewing our supplies of medicines until well past the calling of midnight by the Watch in the street.

The next day we rose at dawn after little sleep, but when we reached the hospital soon afterwards there were already fresh crowds gathered in the old cloisters, begging for treatment. Grimly, we got to work. For the most part, my father passed the babies and children to me, and there were many of them that morning. A young woman, poorly dressed, her eyes red and swollen with weeping, held out a tiny bundle to me.

‘My baby, doctor, he’s been vomiting for two days and passing bloody stools. He won’t feed.’ She gave a shuddering gasp. ‘He isn’t dead, is he?’

The woman wasn’t much older than I, perhaps eighteen, and the baby, when I unwrapped the dirty cloth in which his naked form was wrapped, was tiny and emaciated. For a moment I feared that he was dead, but then he stirred and made a faint mewing cry like a distressed kitten. He was as filthy as the cloth, smeared with blood and faeces. In my work with my father I have had to grow accustomed to many unpleasant sights, but even so my stomach heaved at the sight.

I told the woman to sit down on a stool and sent one of the hospital servants to fetch a basin of warm water and rags, and one of the small pieces of blanket we keep for babies. As I washed the child, I saw even more clearly how thin he was, his ribs standing out stark under the skin like a row of twigs, his rapid heart beat visible to the naked eye. Even as I washed him, he vented a thin stream of diarrhoea, but his stomach was so hollow I could not believe there was much left inside.

The mixture we had made up the night before was too strong for a baby, so I diluted it with goat’s milk, something my father had introduced into the hospital, having found in Portugal that it answered well in the treatment of delicate stomachs. The hospital authorities had viewed it with suspicion at first, but by now it was accepted practice. This infant was too young to drink from a cup or even to take the medicine from a spoon, but we have pottery vessels with a spout, onto which we fit a finger cut from a thin leather glove, with a hole pierced in the end. Sick babies can usually be persuaded to take medicine in this way. As the child had been refusing to eat, I made the mixture more palatable by stirring in a little honey.

At first I feared all my efforts would come to nothing, for the baby twisted his head away and whimpered, refusing to suck from the leather-tipped spout, but at last I managed to squeeze a little on to his tongue. The taste of the honey must have pleased him, for he took the rest readily enough.

‘You must stay here for the rest of the day,’ I told the mother. ‘The child will need another dose this afternoon and again this evening. Keep him wrapped in this clean blanket and if you need a fresh one, ask one of the women servants. I will see you again later.’

‘Will he live?’ The tears had dried on her face and her eyes were bright with hope.

‘I think there is every chance. Now that he has taken both the medicine and the milk. Keep him warm. Do you have family waiting for you at home?’

She shook her head. ‘I lost my first child. Dickon is my only one. And his father is at sea.’

‘Stay here today, and you will be given bread and soup in the refectory. Say that Dr Alvarez sent you.’

I stroked the tuft of fine black hair on the baby’s head, then turned aside to the next patient.

It was a long day and I lost count of how many patients I saw who were suffering from the bloody flux. There were, as well, some of the usual cases needing treatment. A blacksmith’s apprentice with a nasty burn on his hand. A packman whose pony had trodden on his foot. A woman who said she had fallen downstairs, although I had seen the same woman before and knew that she fell regularly against her husband’s fist when he was drunk, but feared him too much to admit to it. However, the day ended well, with the sick baby over the worst, no longer bleeding or vomiting but feeding normally. I told the mother to return the next day so that I could be sure he was cured, but I went home in the comforting thought that, despite my weariness, I had done a good day’s work at my chosen profession. In bed that night I read the same page of Harriot’s book on optics three times, the beautiful Italian words dancing before my eyes. In the end I abandoned it and blew out my candle. My head was too thick to grasp the finer points of the argument.

The next day I was glad to see that the baby was no longer so grey and gaunt.

‘He is feeding well now?’ I asked.

The mother nodded. ‘He even slept a little in the night.’ She gave me a wan smile.

‘Good. Here is a bottle of the mixture, and one of our baby flasks. Give him a third this morning, then again in the afternoon and evening. Keep him clean and warm. If he is ill again, or if you are ill yourself, come back to the hospital at once. Don’t wait two days next time.’

‘I will. God go with you, Doctor.’

She reached out and put her hand on my arm. I laid mine briefly over it.

‘And with you.’

By the end of ten days my father and I were both exhausted, but the outbreak had been halted. Fortunately it had affected none of the butchers, for then, my father predicted, it would have been carried on tainted meat throughout the city. Only a few died, two or three infants – though not the child I had treated – and one old woman, so we were content with our work.

On the first day when I had not needed to rise with the rooster, I was sitting with my father at the table in the kitchen, eating a breakfast of new bread, figs and small ale. I was holding a ripe fig which sat on the palm of my hand like a plump woman in purple skirts sinking down on to a low stool. It smelled softly of southern sunshine and was just at that perfect moment of ripeness when, as we say, it has the cloak of a beggar and the eye of a widow.

My father had made some jest about our needing to take care not to eat too many figs, and we were laughing when the knock came on the door. Joan opened it, and in walked the man Poley as if he were our landlord, come to demand overdue rent. He was finely dressed, in a doublet of slashed blue silk with silver buttons, each garnished with what looked like a ruby – but surely could not be – as large as a robin’s egg. His immaculate ruff spread wide as a trencher, and his cloak of golden velvet was lined with fur. Probably no more than coney-skin, I judged. My father scrambled to his feet and bowed, wiping his fingers on his napkin and dabbing at his mouth apologetically. My heart lurched painfully, for these obsequious manners he had learned in England were so alien to the distinguished professor of medicine at Coimbra university that I remembered from my childhood. I stood up quietly and slipped behind him into the shadows, hoping to edge away through the parlour door.

‘Dr Alvarez!’ Poley extended his hand amiably, as though bestowing a favour. ‘And young Christoval.’ He nodded towards me, for his sharp eyes had noted my attempted escape and foiled it.