I set the dial to eight liters per minute because that’s where Chatterjee had set the old one. Though my focus was on the knobs, I could hear Patrick’s breathing start to even out.

“I think we’re okay,” I said, and looked up.

The nurse Host was standing behind him.

Her head was torqued to one side as if some of her vertebrae had shattered. Her eyeless gaze seemed focused.

She seized Patrick, crimping his tube, and ripped him back over the bed. The tube strained on the H tank, almost pulling off the nozzle.

Patrick’s giant eyes found mine. He was trying to hold his breath in case the tube tore off, but her bear hug was crushing his chest. She whisked him out into the corridor so fast that his legs flew up in the air. The tube pulled taut. I flipped the H tank over the bed onto its side, sending it rolling after them. It clattered as it went, miraculously clearing the doorway, the tube barely holding on.

Hurdling the bed, I took off after them. Patrick swung an elbow, clipping the nurse’s damaged forehead, but she didn’t let go. They fell together, banging into the crash cart and knocking it over, one defibrillator paddle springing out on its cord and snapping back like the tongue of a frog.

As the tank hit its outer limit, the tube went piano-wire tight, yanking the mask straps and Patrick’s head forward. I braced for the tube to pop free, but it didn’t. Instead the rolling tank switched direction, curving in an arc across the tiles, somehow staying tethered to Patrick’s face. Given the weight of the tank, the tube wouldn’t hold it long—it was like having a swordfish on ten-pound-test fishing line. I dove on my stomach and swatted the tank toward them, putting slack back in the line.

She was choking Patrick out now, one arm locked across his throat, the other flailing to cuff his wrist. How could I get her off without tangling in the tubing or knocking it loose?

A glint to their side caught my eye.

The defibrillator paddle.

I lunged for it, sweeping it up and yanking its companion free. I thumbed the charge button on the portable defibrillator. The unit turned on with a whine. It made a series of short beeps and then a long one. I slammed the metal paddles onto the nurse’s head and pulled back on the discharge buttons.

The reaction was unlike anything I’d seen in movies or TV. The nurse jerked back so violently that it looked as though she’d been lassoed. She landed in a sitting position. Electricity fizzled across her eye membranes, sparking, and then they ignited, giving out whooshes of flame. She fell back, her head smacking the floor, and lay still. Wisps of black smoke tendriled up from her eyeholes.