“For evil?” I suggested very dubiously.

“No, for good,” she answered. “I require your silence, and I desire that you should render assistance to one who is sorely in need of a friend.”

“Financial aid?”

“No, finance has nothing to do with it. The unknown person has money and to spare. It is a devoted personal assistance and obedience that is required.”

“But how can one be devoted to a person one has neither seen nor known?” I queried, for her words had increased the mystery.

The shrewd suspicion grew upon me that this curious effort to secure my silence was because of her own guilt; that she intended to bind me to a compact in her own nefarious interests.

“I am quite well aware of the strangeness of the conditions I am imposing upon you, but they are necessary.”

“And if I accept them will the mystery of to-night ever be explained?” I inquired, eager to learn the truth.

“Of that I know not,” she answered vaguely. “Your silence is required to preserve the secret.”

“But tell me,” I said quickly, “how many persons were there present in that house beside yourself?”