I thought my brother’s wife was strange for refusing to sleep anywhere but between my husband and me, until a thin strip of light appeared beneath our bedroom door—and she did something that terrified me.

By the seventeenth night, October had stripped the walnut tree down to black, skeletal fingers. A bitter sleet rattled against the windowpanes like thrown gravel.

The tension in the house had reached a pitch so taut that even the porcelain cups seemed to ring when set upon their saucers.

Tomás had stopped coming down for dinner altogether. Esteban had taken him to the local apothecary two days prior, returning with a dark glass vial of laudanum. “For the agitation,” Esteban had explained smoothly to me while untying his leather gloves. “He was pacing his studio until four in the morning, Elena. He was talking about voices in the floorboards. We cannot allow him to slide into madness again. For Lucía’s sake, if not his own.”

Lucía had said nothing. But that evening, she had not eaten a bite. Her hands had been so numb with cold that she had dropped a tureen of mutton broth, the porcelain shattering against the flagstones.

Instead of scolding her, Esteban had knelt, gathered the sharp shards with his bare fingers, and looked up at her with a smile that made my stomach turn cold.

“Be careful, Lucía,” he had said, his voice soft as thistledown. “Glass cuts so easily. Especially in the dark.”

Now, it was two in the morning.

The fire in the hearth had died down to a dull mound of gray ash with a few sullen, glowing embers. The bedroom was freezing, filled with our mingled breath condensing in the dark air.

I was not asleep. I had not slept properly in two weeks. Every muscle in my neck was knotted with vigilance, listening to the two bodies lying on either side of me.

To my left, Esteban lay on his stomach, his face turned toward the window, his arm flung over the bolster. His breathing was heavy, long, and perfectly rhythmic. The sleep of a man whose conscience had never held a single stain.

Between us lay Lucía.

She had not moved in three hours. She was a line of cold marble dividing the mattress.

And then, the sound came.

It was not the wind. It was not the sleet striking the glass. It was not the house settling on its limestone piers.

*Click.*

It was the sharp, metallic snap of an iron mechanism. Small. Deliberate. The sound of an internal latch sliding back with oiled precision.

My eyes snapped open in the pitch blackness.

My heart surged into my throat, hammering with such violent force that I could hear the blood roaring in my ears.

*What was that?*

The silence returned, but it was not the natural silence of a sleeping house. It was a vacuum. A silence that held its breath.

I began to turn my head toward the door to see if it had drifted ajar.

Before my chin could move an inch, an icy hand slid beneath my blanket.

Fingers—sharp, calloused, trembling violently—locked around my right wrist.

The grip was iron. It was not a plea for warmth. It was not a gesture of affection.

It was an order.

*Don't move.*

Lucía’s fingernails dug so deeply into the tender flesh of my inner wrist that I nearly gasped. But something in the ferocity of that touch choked the sound in my windpipe. Her pulse was racing against my skin like a trapped sparrow, beating at twice the speed of mine.

I lay frozen, staring up at the plaster ceiling medallion, my breath trapped in my chest.

Then, from the bottom of the bedroom door, a sliver of light appeared.

It was so faint at first that I thought my tired eyes were playing tricks on the darkness. But it grew sharper—a cold, yellow line no thicker than a sewing needle, slicing across the dark threshold.

Someone was in the hallway.

Someone was holding a small candle or a shielded lantern, standing directly on the other side of our bedroom door.

The light did not waver. It did not swing as it would if someone were walking down the corridor to fetch a glass of water.

It hovered.

Waiting.

Then came the second sound.

*Tap.*

A single, soft touch against the outside oak panel. The dull, muffled impact of a fingernail brushing against the grain of the wood.

My instinct screamed at me to cry out. To shake Esteban awake, to shout for Tomás, to break the awful spell of the room. I opened my mouth to scream Esteban’s name.

Instantly, Lucía’s grip on my wrist twisted with agonizing force. Her fingers bruised my bone.

*No.*

She didn't speak the word, but the telepathy of terror passed through her flesh into mine.

Slowly, without making the slightest rustle of linen, Lucía shifted her body.

She did not retreat. She did not cower.

She raised herself up by three inches, propping her weight onto her left elbow, interposing her torso directly between me and the closed door. Her head rose, blocking the thin yellow needle of light from hitting my eyes.

She was positioning herself like a shield.

Or a barricade.

And as she moved, my eyes darted across the bed to Esteban.

Esteban had not stirred. His back remained turned to us, his broad shoulders rising and falling in that maddening, measured cadence.

*In. Out.*

Too steady.

Too regular.

No man alive could sleep through the sudden drop in temperature, the sharp *click* of the latch, the shifting of two bodies in the bed, and remain breathing with the mechanical perfection of a metronome.

His left foot, exposed beneath the quilt, was flexed. The tendon in his heel was drawn tight, white and strained, anchoring him to the mattress.

He wasn't sleeping.

He had never been sleeping.

And then, with the sickening force of a lightning strike illuminating a charnel house, the truth shattered my mind.

The person outside the door had not come to attack us.

The *click* had not come from the hallway.

The *click* had come from *inside* the room.

From the bottom drawer of Esteban’s nightstand, where he kept his brass-mounted key ring and his pocket revolver.

The figure in the hallway was not an intruder. The light under the door was not an assassin.

It was Tomás.

Tomás, dazed with laudanum, wandering the halls searching for his wife, terrified to turn the handle because Esteban had forbidden him from approaching our room.

And Lucía...

Lucía was not sleeping in the middle because she was a timid, superstitious girl from the southern provinces.

She was not sleeping in the middle to seduce my husband.

She was sleeping in the middle because she knew that as long as she was wedged between Esteban and his legal wife, Esteban could not lay a hand on her without waking me.

I was not her rival.

I was her human wall.

And the monster she was hiding from was not lurking outside in the winter gale.