“If what?” asked Patrice, half-convinced. “Which was the clue that put you on the track?”

“The presence of that woman at Mantes. It was a vague clue at first. But suddenly I remembered that, in the first barge, the Nonchalante, the person who gave us information—do you recollect?—well, that this person somehow gave me the queer impression, I can’t tell you why, that I might be talking to a woman in disguise. The impression occurred to me once more. I made a mental comparison with the woman at Mantes. . . . And then . . . and then it was like a flash of light. . . .”

Don Luis paused to think and, in a lower voice, continued:

“But who the devil can this woman be?”

There was a brief silence, after which Patrice said, from instinct rather than reason:

“Grégoire, I suppose.”

“Eh? What’s that? Grégoire?”

“Yes. Yes, Grégoire is a woman.”

“What are you talking about?”

“Well, obviously. Don’t you remember? The accomplice told me so, on the day when I had them arrested outside the café.”