Lost Metal is the seventh book in The Mistborn Saga by Brandon Sanderson. The story follows Waxillium Ladrian, a former frontier lawman turned senator, as he continues his hunt for the shadowy organization known as the Set. With conflict brewing between Elendel and the Outer Cities, Wax must navigate a complex web of corruption and intrigue to uncover the truth. Along the way, he discovers a new type of explosive and learns that the Set is under the influence of a new god, Trell. As the fate of Scadrial hangs in the balance, Wax must decide whether to become the hero the planet needs or let it fall into ruin.