Famous painting

Famous painting
'Daddy Jacques,' I said, in a threatening voice, 'you did not follow it; you and the phantom walked to Epinay together - arm in arm!'
"'No!' he cried, turning his eyes away, 'I did not. It came on to pour, and - I turned back. I don't know what became of the black phantom."
"We left him, and when we were outside I turned to Larsan, looking him full in the face, and put my question suddenly to take him off his guard:
"'An accomplice?'
"'How can I tell?' he replied, shrugging his shoulders. 'You can't be sure of anything in a case like this. Twenty-four hours ago I would have sworn that there was no accomplice!' He left me saying he was off to Epinay."
"Well, what do you make of it?" I asked Rouletabille, after he had ended his recital. "Personally I am utterly in the dark. I can't make anything out of it. What do you gather?"
"Everything! Everything!" he exclaimed. "But," he said abruptly, "let's find out more about Mademoiselle Stangerson."