Whose Line is it Anyway? (season 14)

We go to the beginning of the twentieth century. At the center of attention of the plot are events that took place on Saint Valentines day. A group of students of high school with their teachers goes on picnic. They chose a great spot. The main heroines end up on the Hanging rock that captures with its nature beauty. People say this place has not changed its appearance for a million years. But there are rumors it contains a mysterious power inside.