AN OLD MAN IS DYING IN A FINE, RAMBLING HOUSE ON THE THAMES. HE has followed Signor Bruno’s fate carefully. He is a friend—a fellow philosopher and scholar, a man of learning and wisdom. He may be the only other soul alive who is privy to the same extraordinary secrets as Bruno. Elizabeth, the great Queen, had been like his goddaughter and held him in trust for many years, called him her “eyes”—though she too has not very long since gone to her grave. Her successor is the dour Scottish king who is fanatical about ghosts and demons, afraid of anyone who can by any means challenge his authority. The old man has laid low at this, formerly his mother’s house, for several years now.

It is an unusually foggy night just after the March equinox. Lanterns bounce back off the mists as a boat pulls steadily up the river from Chelsea to Mortlake on the rising tide. A shrouded figure stumbles onto the pier in the half-light and makes its way to the door. Ushered in by an upright little woman of uncertain years, the young man flies to the privy chamber of his old master. Candles flicker and almost die from the haste at which he enters.

“Ah, Master Saunders.” His words are spoken softly. “I knew you would come to me, though I was hesitant to demand this task of you. Alas, no one else can be trusted.”

“Your Grace, I am sorry to see you this way. Are you wanting me to help prepare you for this last long journey the angels have spoken of to you?”

The old man manages a grim, ironic laugh. “Journey? Aye, I have lived long enough: I should in truth be on my way. Listen carefully to me, Patrick. I am certainly dying, and time is measured. I cannot answer the questions I know you will wish to ask, but I myself ask that you listen.”

The words come between increasingly short gasps, which only partly reveal the effort they must cost the old man now to speak out.

Slowly he continues: “Next to the three caskets you see here beside me, there is a letter penned by my own hand, which will make clear anything you don’t at present understand. At any moment we will receive three visitors who will perform an operation at my request. Please, do not fear for me, but wait while they are here. When all is ended, they will give you these three chests. Follow my instructions to the letter. Do not deviate, I implore you. It is my last wish, and such a thing is beyond the scope of my dear daughter, Kate. You know it is a lifetime’s thoughts that go with that wish.”