Mary is wondering what is happening as she is definitely seeing bright light whenever she looks out a window. Could her sight be returning?
Naturally, all the family are over the moon about the possibility that their beloved Mary may soon regain her vision but first, it is necessary to travel to the eye specialist with Charles to see if this is actually the case or not.
I don't know about anybody else, but I was truly saddened when the specialist told her that there was a logical explanation for what was happening and that her sight was not going to be restored after all.
We see very little of Melissa Sue Anderson in the show these days but her acting is always outstanding when we DO see her. In fact, the acting in this episode was superb by all concerned, which is probably one of the reasons I felt so sad when it was revealed that Mary would remain blind; I had been drawn into the sense of expectation.