Waving impatiently at a cloud of dust motes in the air, Leo went to the second window, fastening those drapes as well. “So I went outside and noticed that the brickwork pointing is different on the section of the wall where a third window should be. And if you pace out this room and the one beside it—and compare the measurements with the exterior dimensions of the house—it appears there’s an eight- to ten-foot space between these rooms with no apparent access.”


    Poppy flew to the wall of bookcases, examining them desperately. “Is there a door here? How do we find it?”


    Leo joined her, lowering to his haunches and staring at the floor. “Look for fresh scuff marks. The floorboards are never level in these older houses. Or look for fibers caught in the seams between the cases. Or—”


    “Harry!” Poppy shouted, using her fist to bang on a bookcase frame. “Harry!”


    They were all still, listening intently for a response.


    Nothing.


    “Here,” the constable said, pointing to a small white crescent scuff on the floor. “This is a new mark. And if the bookcase swung out, it would correspond.”


    All four of them gathered around the bookcase. Leo pried, pushed, and pounded on the edge of the frame, but the unit remained firmly in place. He scowled. “I know how to find the room, but I’ll be damned if I know how to get inside.”


    Jake Valentine began to pull books from the shelves and toss them heedlessly to the floor. “The concealed doors we have at the hotel,” he said, “are locked according to a pulley-and-dowel mechanism, with a wire running to a nearby object. When you tilt the object, the wire lifts the dowel and frees a doorstop wedge, and the door opens.”


    Poppy grabbed books and tossed them aside as well. One of the volumes she found was stuck in place. “This one,” she said breathlessly.


    Valentine slid his hand over the top of the book, found the wire, and pulled gently.


    The entire bookcase swung open with stunning ease, revealing a locked door.


    Leo pounded on the door with a heavy thump of his fist. “Rutledge?”


    They were all electrified by a distant, nearly inaudible reply, and the quiet vibration of the door being pounded from the other side.


    A few openmouthed servants gathered at the library doorway, watching the proceedings.


    “He’s in there,” Poppy said, her heart thundering. “Can you open the door, Leo?”


    “Not without a bloody key.”


    “Excuse me,” Valentine said, shouldering his way to the door and pulling a small rolled cloth from his coat pocket. He extracted two thin metal implements, knelt beside the door, and set to work on the lock. Within thirty seconds, they heard a distinct clack as the tumblers shifted.


    The door opened.


    Poppy sobbed in relief as Harry emerged, dressed in fencing whites that were gray with dust. Her husband was pale and dirt smudged, but remarkably composed considering the circumstances. Poppy launched herself at him, and he caught her and said her name hoarsely.


    Squinting in the brightness of the room, Harry kept Poppy against him as he reached out to shake the other men’s hands in turn. “Thank you. I didn’t think you’d be able to find me.” His voice was ragged and rough, as if he’d been shouting for some time. “The room is insulated with slag wool to muffle sound. Where’s Kinloch?”


    The constable replied. “He’s at the Bow Street Office, sir, being questioned. What do you say to accompanying us there and making a report, so we can detain him indefinitely?”


    “It would be my pleasure,” Harry said feelingly.


    Ducking behind him, Leo ventured into the dark room.


    “Quite professional,” the constable told Valentine, as he replaced the lock picks in his pocket. “I don’t know whether to commend you or arrest you. Where did you learn to do that?”


    Valentine sent a grin in Harry’s direction. “My employer.”


    Leo emerged from the concealed room. “Little more than a desk, a chair, and a blanket,” he said grimly. “Commissioned you to do a bit of mechanical engineering, did he?”


    Harry nodded ruefully, reaching up to touch a tender spot on his skull. “The last thing I was aware of was something crashing down on my skull at the fencing club. I awoke here with Kinloch standing over me, ranting. I gathered the plan was to keep me locked away until I had developed a set of drawings that would result in a workable gun prototype.”


    “And after that,” Valentine said darkly, “when you were no longer useful . . . what did he intend to do with you then?”


    Harry smoothed his hand over Poppy’s back as he felt her tremble. “We didn’t discuss that part.”


    “Have you any idea whom his accomplices were?” the constable asked.


    Harry shook his head. “I didn’t see anyone else.”


    “I promise you, sir,” the constable vowed, “we’ll have Kinloch in the Bow Street strong room within the hour, and we’ll obtain the names of everyone involved in this wretched business.”


    “Thank you.”


    “Are you hurt?” Poppy asked anxiously, lifting her head from Harry’s chest. “Are you well enough to go to Bow Street? Because if not—”


    “I’m fine, love,” he murmured, smoothing a stray wisp of hair back from her face. “Just thirsty . . . and I wouldn’t mind having some dinner when we return to the hotel.”


    “I was afraid for you,” Poppy said, and her voice broke.