“I’ll tell you if you promise not to laugh.”

“I promise.”

“I’m what’s known as a sensitive. An empath. I have a knack — if you can call it that — for hearing things, sensing things, that people felt or experienced, whether in the present or in the past. This room is…unpleasant. I’ve been hearing music — hearing it in my head. Stan Getz helps me to tune it out.”

“What kind of music?”

“Wild arpeggios, giant clashing clusters of notes, waves of sound. Unsettling melodies, almost insolently virtuosic.”

“You could almost be describing Alkan.”

Logan paused. “You mentioned him before. Wasn’t he a favorite composer of Strachey’s?”

“Charles-Valentin Alkan. Perhaps the strangest composer who ever lived. Yes, Willard was a huge fan. In fact, Alkan was the only composer other than Bach thematically and harmonically complex enough to interest him. I think it was his mathematical turn of mind.”

Logan reapplied himself to the lock, and a second later there came a click as the last pin crossed the shear line. Straightening up, Logan placed both hands on the rosewood cowling and carefully lifted it. Beneath lay a row of buttons, with two knobs — one above the BEAM label and the other above the FIELD label — sporting matching antique VU meters and sets of switches. Everything was remarkably free of dust.

“What do you suppose all this means?” Mykolos asked, putting the camera aside and shaking out her jet-black hair.

“You tell me. You’re the propeller-head, remember?”

For a moment, they looked at the controls in silence. “Do you see anything that looks like an on switch?” Logan asked.

“No. But I wouldn’t look for one near these controls. I’d look on the side, below, nearer whatever machine powers this thing.”

Logan hunted around the base of the wooden housing until he found a much smaller cowling attached to the near edge. Once again employing his lockpicks, he managed to remove it after about ten seconds of manipulating the pins. Beneath were two switches, one marked PWR and the other LOAD.

“Bingo,” Mykolos said, looking over his shoulder, video camera once again in hand, eyes widening in excitement.

Logan reached forward to flip the power switch, then hesitated. “Should we?”

“Won’t get any further if we don’t.”

Gingerly, he took hold of the switch, then flipped it into the on position. At first, there was nothing. Then there came a low humming, almost beneath the threshold of hearing. He placed one hand on the main housing. It was now vibrating slightly.

“Anything?” Mykolos asked as she filmed.

Logan nodded.

“What’s that?” And she pointed to the LOAD switch.

“It probably connects a load from a voltage source.”

“In other words, like throwing a car from neutral into drive.”

“Basically, yes.”

They looked at each other, then at the switch. Even more gingerly this time, Logan reached forward and placed the tips of his fingers on it.

“You think maybe we ought to put on those suits of armor first?” Mykolos said, only half joking.

Logan did not reply. He took a firm grip on the LOAD switch, flipped it into the active position.

Nothing happened.

“Broken,” Mykolos said after a moment.

“Not necessarily. We don’t know the function of all those switches and dials on the front panel. They probably do the real work. But let me see if I can get the rest of these cowlings off first.”

Logan turned off the load switch, then the power switch. The faint vibration stopped and the device came to rest. Then, one after the other, Logan picked the locks of the two wooden housings fixed to the flanks of the device, and then, lastly, the metal plate covering the wide far end. Removing the two cowlings revealed complex gizmos of metal and rubber. One reminded him of a bulky, futuristic antenna; the other a kind of labyrinthine radiator, sporting two rows of horizontal tubes.

He shook his head. It seemed that each bit of progress they made with this strange device just yielded up fresh mysteries.

They bent over the antenna-like device. “What do you make of it?” Logan asked. “Does it ring any bells?”

“Look at this faceplate.” And Mykolos pointed to a legend beneath the contrivance that read, in small letters: EFG 112-A. PATENT 4,125,662. WAREHAM ELECTRIC COMPANY, BOSTON. TOLERANCES 1–20 MG, .1–15 MT.

“ ‘mG,’ ” Logan read aloud. “Do you suppose that’s milligauss?”

“I think so. And I think mT stands for microtesla.”

“Then this thing is a…” Logan fell silent.

“A primitive electromagnetic field generator. And that” — she pointed at the lower section of the assembly — “is probably a rotatable pickup coil.”

Logan took a step back from the machine.

“What is it?” Mykolos asked.

Logan did not reply.

“What is it?” she repeated, frowning.

“One function of such generators,” Logan said at last, “is to detect changes in electromagnetic fields.”

“Yes, I recall that from my electrical engineering courses. So?”

“In my line of work, they’re used for a specific kind of electromagnetic change. Distortions caused by paranormal events.”

Surprise, then disbelief, crossed Mykolos’s face. “You aren’t saying that this was a machine built to…to detect ghosts?”

“It seems possible. Interest in spiritualism and mysticism was big in the nineteen thirties, and—”

“Wait. You’re creeping me out here.” Now it was Mykolos’s turn to take a step back from the machine. “You think this thing was created to detect ghosts…and was abandoned because it didn’t work?”

“Perhaps,” Logan murmured. “Or perhaps because it worked too well.”

Pamela Flood’s office was a large space in the rear of the old house on Perry Street. For a workroom, it was surprisingly elegant. While the antique drafting tables, framed and faded elevations, and technical volumes in old wooden bookcases gave testimony to earlier generations of architects, Pamela had refreshed and brightened the room with several feminine touches.

“Please take a seat,” Pamela told Logan, motioning to a metal stool set beside one of the drafting tables. “Sorry there isn’t anything more comfortable.”

“This is fine.” Logan took a look at the table, noticed it contained a series of architectural sketches in pencil. “You still work the old-fashioned way?”

“Only for the first drafts. Got to keep up with the times, you know. I use a CAD-based software suite to make the customers happy, and I’m also learning BIM.”

“BIM?”

“Building Information Modeling.” She went over to a second drafting table, on which sat several old blueprints, tightly rolled. “I got these out of basement storage this morning. They’re my great-grandfather’s personal set of plans for Dark Gables.”

“Can we examine the diagrams for the second floor of the West Wing?”

“Sure.” Pamela sorted through the rolled sheets of paper, selected one, and brought it over to Logan’s table, where she unrolled it. “I have to tell you, it was something of a struggle not taking an early peek at these.”

“Without me, you wouldn’t have known what to look for.”

“Want to bet?” she asked, smiling. Logan couldn’t help but notice that it was a genuine, and rather winning, smile.

He turned his attention to the blueprint. It was covered with the same crowded lines, measurements, and notes that the set in Strachey’s possession had been. But as he refamiliarized himself with the warren of rooms and corridors, he was surprised to discover that — there, almost directly in the center of the floor — was the very room he had found. A corridor ran along its west wall; flues and mechanical spaces bordered its northern side; and rooms labeled GALLERY and ART STUDIO lay to the east and south, respectively. The room itself was unlabeled.

“Odd,” Pamela said just a few seconds later, placing a finger on the very room Logan was examining. “This room has no doors. And no obvious purpose. It can’t be a staircase — there are staircases here, and here, and another would be redundant. It’s not structural, and it’s not mechanical.” She paused. “It’s possible this is an unfinished blueprint…but, no, there’s my great-grandfather’s signature in the nameplate. How strange.”