When Piero realized I intended to use my bare hands to collect the animals, he interceded. I had to reassure him that, because I was a survivor of the plague, the creatures posed no further threat to me. I opened one of the cages and selected two of the biggest male rats. I tried to grab each nimbly by the tail, but the second one was too fast and managed to bite my finger deeply, drawing blood.

I carried the animals in my sack to a patch of grass several paces behind the monastery. I did not bother to assemble all the ingredients I had invented for the benefit of the Archbishop. Instead, I gathered some dirt and grass and ground them into a coarse paste. I sliced the necks of the two rats and stirred their warm blood into the mixture until it resembled wet mud. I packed the slop into a clay pot.

On my way back, I visited Gabriella. She sat on the bed, staring at the floor.

What is wrong, darling? I asked.

I fear for my brother and sister and their families.

Do you think they will heed my advice and leave Genova?

I am not convinced. My brother is as stubborn as my father was.

If I can appease the Archbishop with this, I said as I raised the pot, then life will be safer for your family.

Gabriella noticed the blood on my finger. What happened?

One of the rats bit me.

She got up and rushed over to me, taking my finger in her hand and bringing it to her lips. She sucked on it as though trying to withdraw the poison of a snake.

It is only a tiny flesh wound, I said with a laugh.

That is how it began with my Ester after the dog bit her, she said fearfully.

The same will not become of me. I have had many such bites of late.

She released my finger, but then she hugged me tightly.

I have to leave for the Archbishop’s palace soon, I said. So that I may return before nightfall.

Why must you go today?

I promised the Archbishop. He might send his soldiers to look for me if I do not arrive. Besides, if this mixture is to have any effect, the blood must be fresh.

What if it is not effective for the ones already afflicted in his palace?

I have considered this. I will tell the Archbishop that the pestilence was too advanced, and that the remedy works better as preventative than as cure.

What if the Archbishop falls ill despite your medicine?

If he is like most of the afflicted, he will be too ill or too consumed to seek out his vengeance.

Gabriella took my hand in hers. Can you really trust him, darling? she asked.

Yes. I uttered yet another lie. By tonight my dealings with the Archbishop will be done, I said. You will see.

I hope so, she said with a stoic expression that could not conceal the deep sadness in her eyes.