“Over my dead body.”

“I’m not afraid to arrange it,” said the ranger, his hand still vibrating an inch over the butt of his gun where it jutted out of his belt.

The captain said, “The dead will have a lot of company if we don’t let that car go.”

Oscar Hayes had his gun out, but he didn’t know where to point it. He wouldn’t shoot the captain, surely, but his wrist was sagging in the direction of the ranger, just in case he needed to shoot someone. Purdue hadn’t budged. The captain and the Texian were so tense, they could’ve twanged like harp strings.

And the Dreadnought pulled them all closer to the pass with every second.

“What have you got back there?” asked the captain. “What have you really got, that’s what I want to know.”

“Dead people. That’s all.”

Mercy decided it was finally time to jump in. She said, “He’s moving a drug called yellow sap. He wants make a weapon out of it.”

Most of the eyes in the caboose and at least one gun shifted focus to aim right at her.

The ranger’s didn’t. He didn’t take his glare away from the scientist, because he already knew what was in the caboose. He added his right hand to his left, and now both palms dangled over both butts of both his guns.

She blurted out the rest. “The dead men back there didn’t die in war. They died from too much sap. But the stuff the sap’s made of—it does a whole lot worse! It makes people crazy, so they eat each other!”

The captain’s gaze whipped back and forth between them. He demanded of Purdue, “Is she telling the truth? Is she?”

Not quite rattled, but taken off guard, Purdue grumbled, “She doesn’t know a damn thing.”

Mercy thought maybe Horatio Korman would back her up, but he didn’t—perhaps because he wanted the scientist and his assistant to forget about him, and fight with the captain instead. So she defended herself, saying, “I do, Captain—please, you have to believe me! And you,” she said to Purdue, “if you want to prove me wrong, then show him what you’re hoarding back there!”

“I want to see your papers again,” the captain said to the scientist. “I want to see who processed them, and who signed them, and—”

“What difference does it make?” demanded Purdue, changing his approach. “Yes, we’re making weapons—that’s what armies do! What’s carried in the last car is important to our program—more important than anything we’ve ever been able to create so far. The potential,” he said, pleading now, almost. “You have no idea what potential.”

Mercy said, “Just this once, Mr. Purdue’s right, Captain. You have no idea of the potential. You have no idea what it does to people—what it could do to the South, yes, but what it could do to anyone. Anywhere. The gas that makes the sap, it kills without caring what uniform anybody’s got on.”

The captain weighed this, even letting his guns lower a fraction of an inch while he thought. He said, “I have my orders, too, Purdue. And I have my men to protect, and you’re not one of my men. Those dead fellows in the back, there’s nothing I can do for them now—and if the Union wants its weapon, the Union can send somebody back here for that cargo. They can forgive me later, or court-​martial me if they’d rather, because by God, we’re—”

Purdue’s posture changed ever so slightly, and at the same time his fingers made the slightest jerking motion. But before he could interrupt the captain with a bullet through the heart, Horatio Korman’s guns were in his hands—both of them, faster than a gasp. He fired them both, one at Oscar Hayes, and one at Malverne Purdue.

Hayes went down without a sound, and Purdue’s rifle muzzle flew skyward, firing one outstandingly loud bullet straight through the ceiling.

Before Purdue could fall all the way to the floor, the captain was on him, kicking the big gun away and pushing his booted foot up against the injured man’s chest. Korman’s bullet had caught Purdue through the shoulder, up near the junction where it met his neck. He was bleeding obscenely; it gushed over his torso as he flailed to stop it, but he failed to push the captain’s boot off his chest.

He burbled, “You can’t. You can’t do it. Everything depends on it! My career depends on it, and maybe the Union—the whole Union!”

Horatio Korman said, “Your Union can go to hell.” And he sheathed his guns with a spin that put them down gentle into the holsters.

“I’d rather it didn’t,” the captain said. He discerned with a glance that Hayes was dead, then checked Purdue. “This bastard might live, at least long enough for me to have him tried. You would’ve shot me.”

“You’re going . . . ,” he gagged. “To cost us . . . everything.”

“No, you were going to cost us everything, and now you aren’t. Ranger, do you know how to undo these couplers?”

“I’m sure one of us can figure it out. If not—” He turned to Mercy. “Mrs. Lynch, how about you run and grab us the nearest porter?”

She nodded and stumbled away, wondering if she should patch Mr. Purdue or leave him, as she suspected that, with prompt and thorough attention, he might well survive the wound.

By the time she returned with Jasper Nichols, the ranger and the captain had managed to disengage the coupler all by themselves, and the rearmost hearse was disappearing slowly into the distance. The Dreadnought put on an extra burst of power to match the ones it’d made in its flight from the defeated meat-​baskets; and, less the weight of the missing car in the rear, the whole train lurched forward with renewed vigor.

Mercy turned to the porter and asked, “What about the caboose? Can we get rid of that, too?”

With a look out the window, he said, “Ma’am, we could, but it might not do us no good. Look.” He pointed, and she saw that he was right.

The Shenandoah was coming up around the curve, wending up the arc of its own track, closing in on the pass. There was a gap of maybe a hundred yards between the end of the Dreadnought and the beginning of the next engine.

Mercy breathed, “Oh God.” And at the same time the captain said, “God help us.” Horatio Korman said nothing.

The porter said, “We’re already too late. Here they come, and here’s the pass. We’re right up on it.”

Besides, as the porter explained, the real weight on the train came from the forward cars and the snowplow attachment—which was to say, the fuel and ammunition car . . . and, as Mercy, the captain, and the ranger privately assumed, the car stuffed with gold bars. But a lighter train meant a faster train, never mind the food stores or the stoves or the cooking units in the caboose. It had to go. All of it had to go. They could grab a new one of everything in Salt Lake City, provided they ever arrived there.

Mercy shoved one arm up underneath Malverne Purdue just as the captain ordered her to do so. She lifted him like an unhappy calf, and heaved him across the couplers into the third passenger car. “Come on, now,” she told him. “And if we get a free minute or two, I’ll do what I can to close up that wound.”

The scientist didn’t object, but he didn’t help her much, either. She dropped him into a seat and patted him down quickly for guns or other weapons. Finding only a small derringer and a boot knife, she took them both and pocketed them. And when she was reasonably confident that blood loss and lack of agency would keep Mr. Purdue out of trouble, she stood up and went back into the aisle.

There, she nearly collided with Captain MacGruder, who said, “Get the inspector over there to help you get him to the next car.”

“What?” she asked, but Inspector Galeano was already at her side, taking the man’s other arm and lifting him back up again. “We’re moving him again?”

“I’ll help,” the inspector said.

“All right,” she replied dubiously, and grabbed the stray, flopping arm of the scientist, who was becoming more rag doll–like by the moment. “If we don’t set him down someplace soon, and for good, we’ll lose him yet.”

Captain MacGruder overheard this, and he said, “Now ask me if I care. Move him up to the second passenger car, and set him down there. If he lives, he lives. If he doesn’t, I’ll shed a little tear and move on with my afternoon.”

He continued to shout orders up and down the line, though since it was he and the ranger who had worked out the coupler disconnects, these two men returned to the gap. In less than a minute, the caboose unhitched and sadly, slowly, slipped away into the Dreadnought’s wake.

The two men flung themselves back inside right before Mercy and the inspector opened the forward door, and she heard him delivering more orders every which-​a-​way behind her. Then she understood. They weren’t just leaving the caboose and the rearmost hearse car; they were leaving this last passenger car, too.

“Everyone, forward!” she heard the Texian cry, and between herself and Inspector Galeano, they wrestled the inert Malverne Purdue into the second car.

Mrs. Butterfield and Miss Clay were startled by the sight of the bleeding man, though neither seemed moved to help settle him someplace. Mercy took care of that herself, lying him down in a sleeper car and feeling at his neck for a pulse, which came more faintly with every breath. The man’s skin had gone white, with a bluish gray around the creases at his eyes and mouth; but the nurse stood by her original assessment that he could yet be saved . . . even if it was only for a court-​martial and hanging.

Mercy stuffed a handkerchief against the wound and dashed to her seat for her satchel, from which she grabbed gauze and wrappings. She applied them to the best of her ability while the inspector served as a silent assistant—taking what she discarded, holding what she needed, and generally doing a damn fine job of staying out of her way. She thanked him with murmurs and tried to ignore the frantic hollers of the passengers, soldiers, and porters as the train lost one more segment and the third passenger car drifted away behind them.