She pushed the certificate toward him. His parents’ names. His grandmother’s signature.

“I don’t understand,” Léon whispered.

“The Baron de Montyon believed in secret generosity,” the woman said. “So I gave you clues. Not to a treasure. To a truth.”

He climbed the narrow stairs. The door was indeed unlatched. Inside, a single candle burned. And there, sitting at a small table, was a woman he had never seen, yet somehow knew.

He was waiting for the Mystère de l’Enveloppe —the Mystery of the Envelope.

“This was your grandmother’s street,” the woman said. “She was the poissonnière at number 12. When she died, she left a box of letters for the son she had to give away—your father. He never came to claim them. I was her neighbor. I watched you walk this street for thirty years, not knowing you were walking over your own history.”

So Léon played along. Each Thursday, he solved the riddle. Each Thursday, he found a small, sad object. And each object, when he investigated, turned out to be a piece of a puzzle he didn’t know he was part of.

Léon sat down heavily. Outside, the rain on Rue Montyon changed its tune—no longer the sound of small hopes, but of a door, finally opened.