He released the edge of the curtain and retreated to the hallway, pausing to duck into the Lincolns’ bedroom and peer out through the window beside a tall wardrobe. Outside it was nearly as dark as inside. He thought he saw motion, maybe a flash of a man running quickly from cover to cover, or maybe only a shift of moonlight on something smaller below. The night was full of raccoons and rabbits, after all.

Knowing this did not prevent him from assuming the worst.

Leaving the window, he carefully walked back to the hallway, where there was almost no light to give him guidance. He worked from memory, from the map in his head of a house he’d visited dozens of times before, though he’d rarely seen these private chambers upstairs, where the aging couple spent their quieter days.

At the end of the hall was an oversized dumbwaiter—or that’s what Gideon had jokingly called the thing when he and Wellers had installed it together last June. It was a closet with a floor built on a lift, an elevator large enough to hold Lincoln and his chair, and perhaps one other person. The structure of the house would permit nothing larger, unless Mary could have been persuaded to give up part of the kitchen pantry. And as it turned out, she could not.

The last room on the left before the elevator was the guest room. Gideon peered through the narrow slit in the curtains, but saw nothing he didn’t already know. Men in the woods. Shadowed figures, distinguished mostly by their movement—and occasionally by a glimmer of brass buttons, the hardware on a gun, or the glint of a spyglass lens.

The hints of spyglass worried him.

He could not tell if the glass was only for observation, or if it was affixed to the barrel of a weapon. Gideon fervently hoped that none of the new recruits were sharpshooters, but he couldn’t count on it; he couldn’t count on anything, not tonight. So he remained wary of any seams in the cloak of darkness they’d forced upon the house. He’d turned off all the gaslights and electric lights, and forbidden any torches—electric or otherwise. Any light within would tell the men without where they were, and offer up a target. It might be a vague target, but it’d be a direction in which to shoot.

Two more rooms to check—and then he was done, and the second story was clear. Back down the stairs he traveled, announcing himself with incautious footsteps, and then calling softly, “Mr. Grant? The upstairs is as tight as I can make it.”

“Good,” came the reply by the front door. But it sounded distracted.

Gideon kept his back to the wall until he reached the president; then he slid down into a sitting position beside him. “They’re collecting more men.”

“I know. And we’re not.”

“They know.”

“It’s only a matter of time, now,” Grant said, low and quiet, “until they come inside.”

“We can hold them off a while longer, put on a show for another hour or two.”

Grant nodded, scratching his salt-and-pepper beard. “I don’t suppose that big brain of yours has come up with any plans, has it?”

Only stalling tactics, but he offered them anyway. “We need to spread out. Put Polly and Mary upstairs, at opposite ends. Let them play sharpshooter, or at least make a lot of noise. By sound alone it’s hard to tell a couple of shooters from half a dozen or more. With them taking the second story and us on the first, we can mount a satisfactory defense that may look like a much better one. And, besides, it gets the women upstairs, where they’ll be marginally safer.”

“Any thoughts how we might send a message?”

“A few. None of them good. We can’t spare a runner right now, and even if we could, we’d be sending someone on a suicide mission … which is why you wouldn’t let Polly go in the first place,” he said, giving a voice to something he’d suspected. Grant didn’t contradict him, so he continued. “Wellers is willing to make a dash for it, but he’d never make it. Mary would have the best chance; she’s a little old lady, and a well-known one at that … but I don’t suppose that’s on the table.”

“No, it isn’t,” Grant said fast. Then, after a pause, “She’d do it if we asked her, though. We’ll work around it.”

“The cellar is a fortifiable position of a kind, but it’s a dangerous one. Only two ways in or out, but, once in, we’d never be able to mount any kind of response. It should be considered, but only as a last option. Not least of all because we’d have to carry Mr. Lincoln down those steps.”

“Doesn’t he have an elevator?”

“Yes, but it only goes between the first and second floors. Structural issues prevented us from sending it any lower or higher.”

“Higher?” Grant’s eyebrow lifted.

“There’s an attic, but it won’t be of any use to us. Just another place to get ourselves stuck. And the cellar is more defensible. I think.”

“I think you’re right.” He sighed. “It’s a damn shame we don’t have that machine of yours here and handy, isn’t it? We could just ask it what to do, and it’d tell us.”

“That’s not how it works.”

“No?”

Since the president seemed genuinely curious, Gideon told him, in brief. “The Fiddlehead collects information, and sorts out the possible results into levels of probability. It can tell you what’s likely to occur, but if you prefer a different outcome, it’s your responsibility to find another path.”

“Ah. Sounds complicated.”

“Of course it’s complicated. If it wasn’t, you’d already have one in every parlor. But,” Gideon added more warmly, afraid he’d been too cold, which wasn’t called for, “it’s a useful kind of complicated. Just not useful to us, personally, right now.”

Outside, they heard men scrambling back and forth, their boots scraping the gravel or whispering through the grass. The wind that had hidden their movements before had all but died, and now the night was a quiet place, and the Lincoln house was listening.

Grant shifted his shoulders and scooted over to the other window, keeping his back to the door and his head below window level. “I think they need another good warning, don’t you?”

Gideon checked his gun. It was fully loaded. “I’ve got enough bullets to say something loud.”

“Good. On the count of three…”

They fired together, not in perfect time, and with less than perfect aim … but the scuttling noises of men coming closer retreated into a scramble of running and ducking as they went back toward the trees. Then, from the east wing, Nelson Wellers fired off a rapid series of four shots, one after the other, so fast that they must’ve been aimed at something.

Gideon stiffened and his knees locked, then he dropped down to the floor and retreated toward the stairs on hands and knees.

Two more shots, and then Nelson either had to reload or grab another gun. He’d taken a second gun—they all had—and now he was using that one, too; Gideon could hear its deafening patter from the other side of the house. It wasn’t the sound of a man giving a warning, it was the violent bass of self-defense.

“Gideon!” Grant called with a sharp, quiet bark that penetrated the distance between them, but not by much.

Gideon paused long enough to look back at Grant, crouched beneath the window with one foot propped on the fallen clock and both hands holding his gun in a ready position: a general turned king, not done fighting even though he’d been told he didn’t need to worry about guarding the castle he’d been given. A thin wash of watery light from the dying fireplace painted him gold and threw a smattering of shadows across his craggy face. He looked older than his years.

But not finished yet.

A louder blast rocked against the door, something harder and bigger than a handgun—something more like a shotgun, Gideon thought wildly. The door shuddered, and the clock that barred it rocked but did not fall. Then a second blast much like the first took out the window in the trestle above Grant’s head. He ducked away from the falling glass as the blanket swung out—then settled again, full of holes.

“Buckshot, that’s all it is!” the president said, waving Gideon away. “A big gun, though—sounds like a punt gun. Don’t worry, I’ve got it. Go on, help Wellers. I’ll take care of this!”

A third blast hit the door again, shattering the lock and shaking the whole portal as Grant slipped past it to the other window. From there, he peered through the edge of the curtain, and carefully—even slowly, thanks to the distraction—took aim and fired.

A loud grunt and a moan, and then the clamor of something heavy being dropped. Close. Very close. Closer than they’d realized. But Gideon knew about punt guns, and he knew you had to be close to make one count.

“Go!” Grant said again, and this time the scientist didn’t argue.

He stood when he reached the hall and was safe from wandering bullets, only to run smack into Mary. He grabbed her by the shoulders, and before she could speak, he said, “Upstairs with you! I’ll send Polly, too, and both of you should run from window to window, and fire at anything that moves. Don’t let yourself be seen, understand?”

“Dr. Bardsley?” Polly squeaked from behind him.

“Did you hear that?” he asked.

“Yes…”

“Then go, both of you. Get up there and stay there, and don’t come down until we give the all clear. Run!”

He released Mary’s shoulders and tried not to worry at how frail they felt beneath his fingers, and how small a woman she really was.

Down the other hall he ran—away from Lincoln, which he didn’t like, but he couldn’t be everywhere at once. For now, no one was shooting down the corridor they were in, so he’d have to pick and choose.

Wellers was reloading. He had to be, for the inside defense had fallen silent. And, yes: As Gideon flung himself down beside his friend, he saw through the window’s shattered edge that men were approaching.