He went slowly downstairs to the office on the ground-floor. The gas was lighted, but there was no one in the room. "Van Duren and Billing have gone out together. If Van thinks I'm going to wait for him, he's mistaken. I'll just shut up shop, and go to tea. Now, what could Van and the other one want in the old boy's room upstairs? That's a puzzler. Is there some little game on that they are all mixed up in? Or are Van and the other trying to best the old 'un? Or is the old 'un trying to best Van and the other one?" Shaking his head, as though the questions he had put to himself were beyond his powers of solution, he took a ledger under each arm, and carried them slowly downstairs--all Pringle's movements were slow--into the fireproof room in the basement of the house, where Van Duren's books and papers were habitually kept. This fireproof room was on the same floor as the rooms inhabited by Bakewell and his wife, who had charge of the whole premises, but was separated from them by a brick passage of some length. Opposite the foot of the stairs was a door that opened into this passage, in which a tiny jet of gas was kept burning through the day. At the end of the passage was a strong iron door, which opened into the fireproof room. There was only one key to this door, and that was kept by Van Duren himself. But it was part of Bakewell's duties to go up to his master's bedroom every morning, obtain the key in question, open the door--which was allowed to stand open all day--lock it again at ten o'clock at night, and take back the key to his master's bedroom. When Van Duren went out of town, which he did frequently, the key was given in charge of Pringle. The key of the safe itself never left Van Duren's possession for more than a few minutes at a time. A small, square apartment with a brick roof, and fitted up with shelves and book-racks, with sundry boxes in one corner, and in the other a large patent safe: such was Mr. Van Duren's fireproof room. Like the passage that led to it, it was entirely shut out from daylight, and the gas was kept burning in it all day long. When Pringle had deposited the ledgers in their proper places, he turned the gas a little higher, and then stood for a few moments listening intently. Not a sound broke the silence. "If one was buried six feet deep in the earth, one couldn't be quieter than one is here," said Pringle, with a shudder. "It's just like a vault, particularly when one knows that there's nothing but dead men's bones all round. No fear of an interruption," he added. "Bakewell's out, and his wife ain't over-fond of this part of the house."