“I’d like a nice quiet little chat with Sibella,” mumbled Heath, busy with his own thoughts.

“It wouldn’t comfort you, Sergeant,” Vance told him. “At the end of your tête-à-tête you’d know only what the young lady wanted you to know.”

“Where do we stand now?” asked Markham, after a silence.

“Exactly where we stood before,” answered Vance dejectedly, “—in the midst of an impenetrable fog.—And I’m not in the least convinced,” he added, “that it was Sibella whom Ada saw in the hall.”

Markham looked amazed.

“Then who, in Heaven’s name, was it?”

Vance sighed gloomily. “Give me the answer to that one question, and I’ll complete the saga.”

That night Vance sat up until nearly two o’clock writing at his desk in the library.

CHAPTER XXIII.
The Missing Fact

(Saturday, December 4; 1 p. m.)