Maya took the key fob to the door of the open plan office, using a broken mirror shard to observe the movement of the zombies. She didn't think she could safely cross the corridor, so she waited for the right moment to throw the key fob into the meeting room.
...
Lin Wu turned the key, and with a 'click', the lock opened. He pressed down on the door handle and pushed the door open with one hand. Inside was darkness, either there were no windows, or the curtains were too good at blocking out light. Lin Wu switched on his flashlight and stepped onto the remarkably soft carpeted floor.
After closing the door, Lin Wu felt along the wall to the window and drew the curtains. He saw the window was sealed with steel bars, like those found on prison windows. The window had not been breached by zombies, and its glass remained intact. After pulling back another curtain, Lin Wu had a clear view of the whole room.