“Where do I go from here?” he asked.

Petronius prodded the fire with a poker. “You shall go at dawn, Colonel, free and clear, as I promise. As to where,” he smiled, “that we shall see.”

“Why wait until dawn?”

As if being forced into telling more than he wished, Petronius put down the poker and wiped his hands on a handkerchief before he faced his client squarely.

“Because only at dawn does your door open — the proper one for you. This is a story at which you may scoff, Tregarth, until you see the proof before your eyes. What do you know of menhirs?”

Simon felt absurdly pleased that he could supply an answer the other obviously did not expect.

“They were stones — set in circles by prehistoric men — Stonehenge.”

“Set up in circles, sometimes. But they had other uses also.” Petronius was all unsuppressed eagerness now, begging for serious attention from his listener.

“There were certain stones of great power mentioned in the old legends. The Lia Fail of the Tuatha De Danann of Ireland. When the rightful king trod upon it, it shouted aloud in his honor. It was the coronation stone of that race, one of their three great treasures. And do not the kings of England to this day still cherish the Stone of Scone beneath their throne?

“But in Cornwall there was another stone of power — the Siege Perilous. It was one rumored to be able to judge a man, determine his worth, and then deliver him to his fate. Arthur was supposed to have discovered its power through the Seer Merlin and incorporated it among the seats of the Round Table. Six of his knights tried it — and disappeared. Then came two who knew its secret and stayed: Percival and Galahad.”

“Look here.” Simon was bitterly disappointed, the more so because he had almost dared to hope again. Petronius was cracked, there was no escape after all.