“National Treasure: Book of Secrets” mixes a bit of conspiracy theory, a dash of treasure hunting, and a hint of a City of Gold to bake up the perfect treat, allowing Nicolas Cage to redeem himself after the horrid 2007 “Ghost Rider.” Cage returns as the honest, persistent, and insanely smart historian Benjamin Gates. Also back for more “treasure” are Diane Kruger as Gates’ now ex-girlfriend Abigail Chase, Justin Bartha’s ever-reliable master of technology Riley Poole, and in a much larger role, Jon Voight as the elder gates, Patrick. The plot begins with Mitch Eilinson (Ed Harris), producing a long-lost page from the diary of Lincoln assassin John Wilkes Booth, of whom Wilkinson happens to be a descendant. The page suggests Ben’s great-great grandfather had a hand in the assassination. Offended yet determined, the Gates men, along with Riley and Abigail, embark on a journey for the truth that sends them to the White House, Paris, London, and eventually the Black Hills of South Dakota, with Harris hot on their trail. Adding to the mix of masterminds is the brilliant Helen Mirren as Patrick’s estranged wife and Ben’s mother, Emily, a historian who studies rare ancient artifacts and languages. With the actors’ great chemistry, a plot that beams with true historical facts and breathtaking locations everyone should gear up for this treasure hunt.