I drive through the gate of the school where I teach to get some documents from my computer. It is 3:30 pm on a Friday afternoon. The school is deserted except for Carol's car. Carol is a dear colleague and very good friend of mine.

As a rule the front door is always locked for security reasons and all staff members have their own keys. I am therefore not surprised to find it locked. I unlock the door, enter the building and lock the door behind me. I walk to my office which is adjacent to Carol's. As I walk past Carol's office, I notice her standing in front of...