#15 - Mary gets by the truck by a few seconds but he hits the next car in line behind her. She goes back to help the people in that car and finds them dead. Realizing how close she came to being the one struck she rededicates her life to her family, friends, and the causes she believes in becoming very close to the family in the car that was hit.
If I allow myself a little dreaming I realize that the above could have happened. So, once again, Mary has given her life to spare the lives of others without even knowing it. She might not have willingly done that for strangers (only she would know) but I know she would have for anyone she loved. It's that old philosophical question about would you save a stranger who is drowning knowing you can't swim very well but you are their only chance?