He was not what he seemed, Grey had said. Not the police officer who’d been tasked with guarding her door. Someone else.

The man tried the handle to Grey’s hospital door. When he found it locked, he used his elbow to break the glass, then put his arm through and unlocked it from the other side. He slipped into Grey’s room and shut the door behind him.

“We have to go now,” Grey whispered. “Follow me.” She opened the door and padded quietly into the hall, her feet bare, tiny drops of blood slipping from her hand as she moved. My own blood was thundering rapids, but my footfalls were silent as I followed her, also barefoot, crouching low as we moved past her room, careful not to step on any glass as we moved under the broken window.

“You have to hide,” Grey whispered to the doctor as we crept back past her. The nurse had already disappeared, but the doctor was now an empty shell, gone from her body. There was a crash from Grey’s room, an animal growl: He’d found her bed empty. The doctor looked that way and swallowed but didn’t move. Grey knelt by the woman’s side, tucked a strand of her hair behind her ear, and then leaned in to press her lips against hers. It had been a long time since I’d seen Grey do this thing, and for a moment I wondered if it would still work, but then whatever sweet potion we carried on our breath, our lips, every inch of our skin worked its way into the doctor’s bloodstream, and I saw her melt beneath my sister’s touch. When Grey pulled back from the kiss, the woman’s pupils were saucers, and she looked at Grey like a bride walking down the aisle on her wedding day. Awed. Overwhelmed. The most in love she’d ever been. “Hide now,” Grey said. The doctor smiled, punch-drunk and dazed, and slipped into the room behind her.

My pulse was a flurry. “Come,” I whispered urgently. We ran then, hard but silent, toward where Vivi and Tyler slept, rounding the corner as Grey’s door slammed open, sending more broken glass jittering across the floor. The noise made Tyler jump awake. Grey pressed her palm over his mouth and shook her head. Tyler swallowed. I woke Vivi with a finger against her lips. Her eyelids lurched open, but she was quiet as I pulled her to her feet and motioned for her to take her shoes off, carry them in her hand. Grey removed her hand from Tyler’s face and knelt to help him pull his shoes off.

All was silent. Then came the crunch of heavy boots on glass. The footfalls were headed in our direction, following the line of blood drops Grey had left on the floor. Vivi put her backpack on. Grey pulled Tyler out of his seat and wiped her hands on her dress, and then the four of us moved softly, swiftly toward the next hallway, making it around the corner a moment after the man stepped into the waiting room, the shadow concealing our retreat. I watched his diluted reflection in a panel of glass. There were three fresh runes written down his chest in blood. He crouched and placed his palm where I had been sitting. He picked up Vivi’s rolled-up jacket from the floor and pressed it to the stripped-bare bones of his mask, inhaling deeply. He nudged Tyler’s shoes with his toe.

From the back of his waistband, he pulled his gun and started in our direction. We peeled away from the wall we’d been pressed against and ran soft-footed down the corridor, as quickly and quietly as we could manage.

As we rounded the next corner, Grey slammed into a body. A green aura of stink exploded in my head.

“He—” breathed the figure (a woman, I could see now, in the half-light), but Grey drove the scalpel up under her chin and cut off her cry when it was still no more than a breath. Grey yanked the scalpel out of her head and held the woman tightly against her as she lowered her, gushing blood, to the floor. The blood was full of clots and smelled of decay.

We kept running in the dark then, turning corners, backtracking when figures appeared at the end of a hall or when a wall of smoke and rot stench hit us. Grey was doused in blood—but was it blood? In the half-light, the stain down her front seemed to twitch across her like shadow.

“We need to get off this floor,” Grey whispered. “Out of this hospital.”

“There,” I said, pointing to a door at the end of the corridor. EMERGENCY EXIT ONLY, it read. ALARM WILL SOUND WHEN DOOR IS OPENED.

“Do it,” Grey said. “Run, and don’t stop running.”

We ran. Vivi reached the door first, slammed into it at the same moment the alarm split my teeth open. I followed her, and Grey came up behind me. Tyler hurled himself through the door last. When I looked back, the man was coming straight for us, the bone of his mask catching shards of light as he charged in our direction.

“Go, go, go, fucking go!” Grey screamed as Tyler pulled the door closed, the man hitting it three seconds behind us, popping it from its hinges like a craft Popsicle stick. We flew down the stairs, taking them three at a time, our feet slapping the concrete, our lungs sucking hard. The man was fast and agile. As we tore down the stairwell, gripping the handrails to swing around corners faster, we heard him gaining on us. Then we smelled him gaining on us. Then we felt him gaining on us, the wet hotness of his breath, flecks of sweat from his arms and chest flicking the back of my neck. Tyler screamed. I turned. The man held him by the collar and had him pressed up against a wall. Grey was already there. She plunged the scalpel into the creature’s chest and fell back. The gun went clattering down the stairwell, lost somewhere below us. The surgical implement looked comically small lodged in his flesh, a toothpick stabbed into a watermelon. He dropped Tyler, who scrambled toward us, choking. We backed away, down the stairs, as he plucked the scalpel from his chest like a splinter and flicked it to the ground, where it made a pretty twinkling sound.

“Run,” Grey said. We turned and hurled ourselves downward again, out the door at the bottom of the stairs and into the cool night. After the shrill alarm of the stairwell and the thick stink of the horned man, the night felt crisp and quiet. We’d been spat out at the back of the hospital.

The man burst out of the stairwell behind us, clipping the horns of his mask on the doorway.

Grey was the fastest out in the open and she ran hard through the gap between hospital buildings until she reached the street, where she flung herself in front of a passing car. It screamed to a stop, curls of rubber smoke rising from the asphalt beneath it. The driver wound down his window and started yelling obscenities. Grey pitched herself through the window and planted a desperate kiss on his lips. The man went quiet as she spoke in his ear, quickly, urgently, as we all piled into the car. Then Grey folded into the back seat, and the man shoved the car into first and smoked the tires again before we’d all even closed our doors—and not a moment too soon.