Instruct: Classify Amazon reviews into positive or negative sentiment
Query: The Concealed Mystery

Over Sea, Under Stone, by Susan Cooper, supports the theme of the search for the Holy Grail, and the fight over good and evil. Like in the legend of King Aurthur, the Holy Grail is the key to winning the seemingly never-ending battle of good and evil in this amazing novel. This story is mainly about three children, Simon, Jane, and Barney Drew. The Drew children, visiting their great uncle Merry stumble upon a secret opening to the attic, where they have lunch. What they find in the attic begins a quest for the Holy Grail that results in a thrilling and suspenseful novel. The excitement in this story makes it a must read for junior high students interested in the Arthurian legend.