It is the first time that I watch a whole drama with English only. At first it was so difficult to distinguish the cast and to catch them exactly, for I was still not rather familiar with the quick subtitle. And it costs me about three days.
I have searched some information online before having it watched and I come to realize why this is recommended by my teacher.

Based on the real cruel event of Salem Witch Trials, this drama focuses more on the divinity of inner world. Because of envy to Elizabeth, who is the dear wife of her lover, Gabile curses E and thus dances with her fellows. Later, she deceives the townspeople and forces her fellows to behave like her. This has aroused the horror of the whole town. The witches seem to be everywhere.