Then something changed. A year ago, when the roundness of my face began to fall away and the edge of my bodice grew tight, I could ignore it no longer: the feeling of another gaze, a new one, and the sensation that someone watched me too closely.

It was Mr. Amwell, my mistress’s husband. He had, for reasons I could only faintly understand, begun to pay attention to me. And I felt sure my mistress sensed it, too.

It was almost time. My bellyache was not so bad anymore; moving about the kitchen seemed to help. I was grateful for it, as following Nella’s instructions would require me to be careful and steady. A slip of my hand, which might be laughed about in my mistress’s drawing room, would be very bad today.

The two smaller eggs sizzled in the pan. The fat spit onto my apron while the white edges of the egg bubbled and curled. I remained still, concentrating, and spooned the eggs from the pan when the edges reached the color of honey, just as the mistress liked. I placed her eggs on a plate, covered them with a cloth and set them far aside. I then spent a few minutes tending to the gravy, which was Nella’s suggestion.

As the gravy thickened, I realized it was the final moment to undo what I had not yet done, to strip out the thread which had not yet been sewn in. If I followed through, I would be like one of those men at Tyburn that I’d heard about at the hanging day fairs: a criminal. Gooseflesh scurried across my skin as I thought of it, and I considered briefly the idea of lying to my mistress—telling her that the poisoned egg must have been too weak.

I shook my head. Such a lie would be cowardly, and Mr. Amwell would remain alive. The plan—which Mrs. Amwell had set into motion—would fail because of me.

I wasn’t meant to be in the kitchen at all today. Last week, Sally had asked Mrs. Amwell for a few days away to visit her ailing mother. My mistress had readily approved and, afterward, called me to her drawing room for another lesson. But this lesson was not about penmanship or letter-writing; it was about the hidden apothecary shop. She told me that I was to leave a note in the bin of pearl barley just inside the door of 3 Back Alley, and that the note should specify the date and time I meant to return for the remedy—which was, of course, a deadly one.

I did not ask my mistress why she meant to harm her husband; I suspected it was because of what happened a month ago, just after the new year, when my mistress left the house and spent the day at the winter gardens near Lambeth.