"The world . . . is . . . hollow." This is the secret that Chunth, the Tel-Jilad troll elder, entrusts to Glissa Sunseeker before his death at the hands of a traitor. Armed with that knowledge, Glissa fights her way through the great vedalken capital of Lumengrid, down into the Pool of Knowledge. The Synod's sacred chamber contains a lacuna--a tunnel, saturated with blue mana--that leads to Mirrodin's secret interior. There, huge, bizarre towers of funguslike metal called mycosynth reach up toward an immense inner sun of pure mana.