Olympus, California has made it big as one of the most popular sites of the 1849 Gold Rush, but its title is in jeopardy when a mysterious self-proclaimed vigilante, The Ghost King, threatens to turn Olympus into a ghost town. Renowned "Horse Whisperer" Percy Jackson is hired by Mayor Castellan to analyze The Ghost King's horse, Blackjack- can he get to the bottom of this mystery and save the townspeople?