A loud horn began to blare throughout the entire floor.

It was a deep, mechanical horn that sounded three times.

The heavy steel fire doors at both ends of the hallway began to slide shut.

These were the pneumatic quarantine doors, designed to seal the wing in case of an airborne infection.

“Lockdown,” a computerized voice announced over the intercom. “Clinical quarantine initiated.”

The security men looked up as the massive steel doors began to descend from the ceiling.

The lead man yelled something into his radio, his face turning red.

He abandoned the nurse and ran toward the closing door.

He threw his heavy equipment bag into the gap to stop the door from sealing.

The steel door crushed the bag with a sickening crunch, but the safety sensor triggered.

The door began to slide back upward.

“Ethan!” I cried.

Ethan was already running back toward me, his face pale and covered in sweat.

He grabbed my waist and pulled me toward the nearest alcove.

“The doors will cycle again in thirty seconds,” he said. “We have to get inside the clean room.”