Princess Celestia urgently arrives at Twilight's Castle. She asks for Mighty Targe, Twilight's only royal guard, to rejoin his old co-workers for one final mission. They must travel to Appleloosa to find a mysterious gemstone that threatens all of Equestria. But not all is what it seems. Friends and enemies alike show their true colors when power is at the tip of their hooves. Mighty Targe faces many of these threats, but will his choices lead to Equestria's salvation or its fall?