Johann Gutenberg, a driven and caustic inventor, has devised a revolutionary—and, to some, blasphemous—method of bookmaking: a machine he calls a printing press. Fust is financing Gutenberg's workshop, and he orders Peter to become Gutenberg's apprentice. Resentful at having to abandon a prestigious career as a scribe, Peter begins his education in the "darkest art."

As his skill grows, so too does his admiration for Gutenberg and his dedication to their daring venture: printing copies of the Holy Bible. But when outside forces align against them, Peter finds himself torn between two father figures—the generous Fust and the brilliant, mercurial Gutenberg, who inspires Peter to achieve his own mastery.