The Plague Forge
by Jason M. Hough
After discovering the first key in the wreckage of a crashed Builder ship, Skyler Luiken and his crew follow the migrating aura towers in search of the four remaining relics. But time is running out: the team learn that the next Builder event will be the last, and one of the objects has already fallen into dangerous hands. . . Will the survivors finally reveal the Builders' plan?