In Harry Potter's sixth year at Hogwarts, he finds a potions book, which used to belong to the very mysterious Half-Blood Prince. Harry finds that the Half-Blood Prince's ancient scribbles written in the margins give him great advice on how to improve on his Potions work, and also teach him a few helpful spells along the way. Harry will have to put these spells to good use in the wake of Lord Voldemort’s return.