The fate of the Mountain hangs in balance at the time of Equinox, and even the Keep can no longer remain untouched. The Maelir are desperate to defend it, the Faemir to demolish it, the windriders to claim it. But unknown to them all, a dark force has already emerged from the chaos to seize power.
As Atreu and Verlinden strive to decipher the power of the Talisman that has defined Atreu's Ascent, Teyth and Valkyra are locked in a desperate battle that neither of them can win. At a time when darkness and light are in perfect equilibrium, when Maelir and Faemir must find a way to break the deadlock and avoid annihilation, the world's fate lies in the Book of Ascension.