Check out the labs

You turned sharply to your right.  You headed down the corridor that was behind you.  As you entered the corridor, you thought you heard footsteps behind you.  Most likely, there was someone coming up the stairs.  You needed to get out of the corridor before they got to the second floor, looked down the corridor, and spotted you.

The doors that lined the corridor were solid.  The lights in the corridor were so dim that it was impossible to read the placards on the doors.  There was no way to tell what was on the other side.  All the doors were closed.  They were supposed to be locked.  Card readers allowed students and faculty access to those labs they were authorized to use.

More out of desperation than expectation, you tested the doors at random.  You were surprised when the third one you tried gave when you pushed on it.  Off balance, you fell.  You yelped as you hit the floor.  There was a soft click as the door closed behind you.  Still on the floor, you looked around to see where you were.