At the same time Dr. Nathan Andrews -- the one character that connects the entire film trilogy -- is trying to find the parents of a boy who died in the ER .
Mark is trying to help one of his son 's friends .
At the same time Dr. Nathan Andrews -- the one character that connects the entire film trilogy -- is trying to find the parents of a boy who died in the ER , and Mark is trying to help one of his son 's friends .