Long tables are being looted from other rooms and chivvied into the library by glossy-haired young men in uniform, knocking flecks of paint off the doorframes. Waterhouse takes an arbitrary chair at an arbitrary table. Another aide wheels in a cart of wire baskets piled with file folders, still smoking from the friction of being jerked out of Bletchley Park’s infinite archives. If this were a proper meeting, mimeographs might have been made up ahead of time and individually served. But this is sheer panic, and Waterhouse knows instinctively that he’d better take advantage of his early arrival if he wants to know anything. So he goes over to the cart and grabs the folder on the bottom of the stack, guessing that they’d have pulled the most important one first. It is labeled: U-691.