Mercy said, “You’re daft!” but she was already getting excited about the plan.

“I’m daft, and I’m going. And I require your medical . . .” She almost didn’t say it, but in the transparent hope that flattery might get her someplace, she finished with, “expertise.”

“Oh, for the love of God.”

“Please, Mrs. Lynch. The repairmen are finished with the rear compartments, and they’ve moved on to the engine and the broken windows in the first car. We won’t be here more than another hour.”

Mercy said, “Fine,” folded her satchel up, and left it on her seat. She rose and adjusted the gunbelt she now wore more often than not and draped her cloak over her shoulders without raising the hood.

As she followed Theodora Clay out of their passenger car and onto the next one, she did not mention that their errand might prove to be a race against time. She did not tell her companion about the Shenandoah, the Confederate engine that had ridden a northwestern track in order to bring those meat-​baskets up to the plains and unleash them on the Dreadnought. She did not mention that she had indeed been talking to the Texian, and that he believed the Shenandoah was still following, tracking to the south and east, but closing ground, despite its defeat. If he was lucky, Horatio Korman was in the process of retrieving a telegram that would inform him of how correct his suspicions were. And if they were all lucky, it would say that the Shenandoah had given up, turned around, and headed back down to Dallas.

Meanwhile, the engine halted in Denver for only a few hours when it ought to have stayed overnight for an inspection; because a telegram from Union intelligence had been waiting in Denver, no doubt warning of precisely this same possibility and urging haste in any repair work.

While the train sat there, grounded and undergoing the improvements that would keep it rolling the next thousand miles, Mercy Lynch followed Theodora Clay to the spot between the last passenger car and the caboose. It was strange to stand on the junction without the wind putting up a fight, but no stranger than watching Miss Clay scale the external ladder with casual quietness and then, from the top of the car, pivot on her knees and urge Mercy to join her.

When she reached the top rung, Miss Clay whispered, “Move slowly and be quiet. Discretion is the better part of valor in this instance. If we make too much noise, they’ll hear us inside.”

“Sure,” said Mercy, who then pulled herself up on top of the steel-​and-​tin roof, sliding on her belly like a seal and then climbing to an all-​fours position. Her skirts muffled the knocking of her knees, and her wool gloves kept the worst of the frigid surface’s chill from getting through to her fingers. But even with the thick layers of clothes, she could feel the cold seeping up through the fabric, and onto her shins, and into her palms.

The nurse had the feeling that Denver was a gray, smoky place under the best of circumstances, and while the Dreadnought was being addressed in its station, a layer of dirty snow hung over everything. It blurred the edges between buildings, sidewalks, streets, and interchanges, and it made the air feel somehow colder. Atop the caboose, which they very slowly traversed in inches that were gained in calculated shifts, slides, and steps, there was little snow except what had fallen since they’d stopped. This snow was a funny color, more like frozen smog than shaved ice. It collected between her fingers and soaked along her legs and elbows where it met her body heat.

Around the train, men hurried back and forth—most of them soldiers or mechanics, bringing sheets of glass and soldering equipment up to the front of the train; but over the edge Mercy could also spy a station manager with stacks of envelopes, folders, ticket stubs, and telegraph reports.

All she could do was pray that no one looked up.

Even if the women flattened themselves down, anyone standing close enough to the caboose could likely stand on tiptoe and see what they were doing. The crawl was torturous and time consuming, but in what felt like hours (but was surely only ten minutes) they had traversed the car and were prepared to lower themselves back down onto the next platform, the one between the caboose and the final car.

On her way down the ladder, Theodora Clay hissed, “Mind your step. And stay clear of the window.”

Mercy had every intention of following these suggestions to the letter. She slowly traced Miss Clay’s steps down the ladder, across the pass, and then up the next ladder, approximately as silently as a house cat wearing a ball dress. On her way to the top of the final car, she looked over her shoulder to peek through the caboose window, where she saw the back of Malverne Purdue’s head bobbing and jiggling. She thought he must be talking to someone she couldn’t see, and hoped that she wasn’t in the other speaker’s line of sight.

By the time she was situated and stable, Theodora Clay was already prodding at the edges of the emergency hatch, or ventilation hatch, or whatever the portal’s original purpose might have been. Mercy crept to her side and used the back of her hand to brush the small drifts of snow away from the hinges and seal. Before long, she spotted a latch.

Mercy angled her arm for better leverage and gave the latch a heave and a pull, which Theodora Clay assisted with when the nurse’s progress wasn’t fast enough to suit her. Between them, they forced the handle around and then heard the seal pop, its rubber fittings gasping open.

Theodora Clay asked, “Why would they seal it with rubber, like a canning jar?”

Mercy was already rocking back on her knees, her hand to her face. “To keep the cold in. Or . . . good God. To keep the smell contained! Lord Almighty, that’s . . . Ugh,” she said, lacking a word with the appropriate heft and reaching instead for a gagging noise.

Her companion didn’t do much better. She, too, covered her mouth and nose, then said from behind her hands, “The smell of death, of course. I’d think you’d be accustomed to it, working in a hospital like you have.”

“I’ll have you to know,” Mercy said, her words similarly muffled and choked. “We didn’t have that many men die on us. It was a very good hospital.”

“Must’ve been. Is there a ladder or anything to let us descend?”

“I don’t see one,” Mercy said, taking a deep breath of the comparatively fresh air outside, then dipping her head down low to get a better look. “And there’s more to that smell than just death.”

Inside, she saw only darkness; but as her eyes adjusted, she saw elongated forms that were surely coffins. Her breath fogged when she let it out, casting a small white cloud down into the interior. She sat back up and said, “I see caskets. And some crates. If there’s no better way, we could stack them up to climb back out again. But when they open the car in Boise, they’ll know someone got inside,” she concluded.

“Maybe. But do you really think anyone would believe it was us?”

“You’re probably right. And as for getting down . . .” She held her breath again and dropped her head inside for a look around. When she came back up for air, she said, “It’s no deeper than a regular car. If we hang from our hands, our feet’ll almost touch the floor.” Mercy said, “You first.”

Miss Clay nodded. “Certainly.”

She did not ask for any assistance, and Mercy didn’t offer any. It took some wrangling of clothing and some eye-​watering adjustments to the interior air, but soon both women were inside, standing on a floor that was as cold as the roof above. The compartment was almost as dark as night, except for a strip of glowing green bulbs, the color of new apples, that lined the floor from end to end. They barely gave off any light at all, and seemed to blow most of their energy merely being present.

But the women used their feeble glow to begin a careful exploration of the narrow car, which was virtually empty except for the crates and the coffins. If the crates were labeled at all, Mercy couldn’t detect it; and the coffins themselves did not seem to have any identifying features either. There were no plaques detailing the names or ranks of the men within, only dark leather straps that buckled around each one. Each one also had a rubber seal like the hatch in the roof.

Mercy said, “I’m opening one up.”

“Wait.” Miss Clay stopped her, even as her hand went to one of the buckles. “What if it is some kind of contamination?”

“Then we’ll get sick and die. Look, on the floor over there. They’re coupler tools, but you can use one as a crowbar, in a pinch. Or you can see about opening some crates, if you’re getting cold feet. This was your idea, remember?”

“Yes, my idea,” Miss Clay said through chattering teeth.

“Ooh. Hang on,” Mercy stopped herself. “Before you start, let’s stack up a box or two so we can make a hasty exit, if it comes down to it.”

Miss Clay sighed heavily, as if this were all a great burden, but then agreed. “Very well. That’s the biggest one I see; we can start there. Could you help me? It’s awfully heavy.”

Mercy obliged, helping to shove the crate under the top portal, and then they man-​hauled a smaller box on top of it, creating a brief but apparently sturdy stairway to the ceiling.

Miss Clay said, “There. Are you satisfied?”

“No. But it’ll have to do.”

Even though she’d been offered the alternative activity of checking the crates nearby, Theodora hung over Mercy’s shoulder while she unfastened the buckles and straps and reached for the clasps that would open the coffin.

Mercy said, “Before I lift this, you might wanna cover your mouth and nose.”

Miss Clay said, “It does nothing to offset the odor.”

“But there may be fumes in there that you don’t want to breathe,” she said, drawing up her apron and holding it up over her face in an impromptu mask. Then she worked her fingers under the clasps and freed them. They lifted with a burp of release.

More outrageous stench wafted up from the coffin, spilling and pooling as if whoever was lying inside had been breathing all this time, his breath had frozen into mist, and this mist was only now free to ooze tendril-​like from the depths of this container. It collected around the women’s feet and coiled about their ankles.