chunk: Two-and-a-half months later, as Darzac's trial opens, Rouletabille reappears sensationally and tells the court that the culprit is Frédéric Larsan himself, whom he accuses of being an alter-ego of a master criminal called Ballmeyer. Larsan appeared to vanish on the two occasions he was nearly collared as he was one of the pursuers. Darzac is released when it emerges that Larsan has vanished after Rouletabille warned him he would accuse him in court. The mystery of the locked Yellow Room is explained thus: Larsan assaulted Ms Stangerson earlier in the day than originally thought, but she hid the traces of the attack and locked herself. During the night, traumatised by the event, she fell off her bed and inflicted the gravest of the wounds by hitting her temple on the corner of her bed-side table.