“Thank you,” I said, approaching the mavka. “Is there anything else I can do to repay you?”

She stared at me and Vanya in silence, her hazel eyes darkening to black as the sun sank below the trees. A ghost of sadness drifted over her features.

Who were you once? I wanted to ask her. You must have had a name. Had a family. What happened to you?

Young women who died in the woods became mavki. I wondered, had she died naturally or was she murdered? Had it been quick and painless, or had it been terrifying?

Without a word, the mavka turned away and retreated into the underbrush, leaving me and Vanya alone at the cave’s entrance. I tugged on the door of the grate, but it was locked tight, no way inside.

“Let me try,” Vanya said, and he bent down to bury his hands in the earth. I retreated to a safe distance as roots punched through the soil and ensnarled the grate. The ground split with an earthen rumble, followed by the groan of twisting metal as the roots pried apart the bars. Within moments, the grate gave way, exposing the darkness of the tunnel beyond.

“Can I have some of your coat’s lining to make a torch?” I asked Vanya as we stopped in the shadow of the rock overhang.

“Fine, let’s destroy my only set of clothes,” he grumbled, unbuttoning his coat. My skin crawled at the rasp of tearing cloth. Moments later, he rebuttoned his coat and handed me a strip of cotton.

I found a thick branch in the drift of debris that last season’s flooding had deposited at the cave’s entrance and wrapped the cloth around the top of it. After saturating the cloth in gun oil, I lit it with a match.

As we entered, it was like being consumed—a clammy darkness with many teeth. Deeper, deeper, we went into the hill, passing several pools of unknown depth. Overhead, limestone stalactites hung from the ceiling, the outcroppings rimed with bands of crystal that glistened like saliva in our torchlight.

I walked close enough to Vanya that I could make out the stitches on his neck. In all the children’s stories, the bogatyr and the tsarevna had a rushnyk tied around their clasped hands during their wedding ceremony, binding them for life. Vanya and I were bound now, too, with the thread of a rushnyk, with my own blood and labor.

Soon enough, in a cavern so low we had to duck our heads, we came across the first sign of human disturbance—a heap of rotting buckets discarded near a hole eroded in the ground. A pulley system was bolted to the ceiling, and the remnants of a rope dangled into the darkness below. I looked into the hole. Although it was too dark to see to the bottom, I heard the splash of water.

We kept going. Past the natural well, the tunnel widened into a cavern divided into sections by brick walls. Trestles suggested that the room had once been used for storage, but all that remained were broken barrels and rusted bands.