Fournier was up now, unveiling a painting on another easel, a still life of fruit and flowers. “I know this painting is legitimate. I purchased it from the most reputable gallery. Its provenance is undeniable.” He snatched the turpentine cloth from Vincent’s hand and dragged it over a tiny corner of the still life. When he turned the cloth around, it was clean.

“At least you have one legitimate painting,” Vincent said.

Fournier scowled as he unveiled the third painting, a Venetian scene. “Canaletto,” he said. “Purchased at the same gallery. I have the provenance papers of authentication to prove it.” He whisked the painting with the turpentine cloth. Here too, it came away clean. Then he unveiled the fourth and last painting, which Vincent recognized immediately.

“This one you also purchased from Monsieur Chaudron,” he said.

“How do you know?”

“Because I saw it in his studio. It is called Le Chemin de Sèvres. The original hangs in the Louvre.”

With his mouth set tight, Fournier dragged the damp cloth across the landscape. It came away stained with color. Now he turned back to his Mona Lisa, staring hard at the initials. He tested the surface again in another corner, and one more time, the cloth came away blemished by pigment.

“I thought she was mine,” he said, his voice a mix of disgust and defeat. “What a fool I was.”

Vincent would have agreed, for he felt no pity for him, but he needed his help. “We are both fools.”

“I want them dead!” Fournier said.

“But first you want your money back, no?”

“Can you find them?” Fournier asked.

“I am determined to do just that. But I have no idea where they might be. I hoped you would know.”

Fournier shook his head, then stopped. “Wait… I bought another painting from Valfiero just a few months ago.”

Vincent asked to see it.

“I sold it,” Fournier said. “It is probably another forgery, and if so, I am now implicated. But that is not the point. What matters is how I bought it and where—from Chaudron’s studio in the south of France.”

“And you have been there?”

“No,” Fournier said. “I sent a courier. I had been given a daguerreotype of the painting. I paid half before, the other half when it was delivered.”

“Whom did you pay?”

“Valfiero. He was always the intermediary, the businessman. I never met Chaudron.”

“And this courier, you can reach him?”

“There is no need.” Fournier turned to a small desk and slid open the drawer. “Here,” he said and handed Vincent a small card. On it, the name Café Bleu. “It is in the town of Lacoste, in the Vaucluse region. That is all I know, all that Valfiero would tell me, and all that I was allowed to tell my courier.”

“So your courier went?”

“Yes. He met Valfiero in the café, where money was exchanged for the painting.”

“And you say this was only a few months ago?”