St Trinian's 2: The Legend of Fritton's Gold 2009 ( 5.6)

After a wealthy philanthropist expresses an unusual interest in a ring found by her niece Annabelle, Miss Fritton explains that she's descended from a pirate who, in 1598, stole treasure from another: the philanthropist's ancestor. This discovery sends the racuous girls of St. Trinians on the hunt for buried treasure.