"We two ought not to die before we have explained ourselves to one another."

John Adams wrote those words to Thomas Jefferson early in the long series of letters they exchanged near the end of their lives. In Madison's Cave is Jefferson's imaginary explanation, organized around four drawings that he hopes will map the route to a complete emancipation of human nature. The souls of men are demons, Jefferson begins, but he is convinced that he has built a verbal machine to exorcise them, a mechanism hidden in the pages of his notorious Notes on the State of Virginia.

The key to the machine is the outline of a limestone cave in the Shenandoah Valley that Jefferson made not long after the death of his wife and that captures, for him, the essence of the human underworld, its monsters and its redemptive lessons. In a series of chapters that mimic those of his infamous book, he ushers Adams into that underworld. This experimental epistolary novel considers early American history, government & politics, education, race relations, and other themes that still resonate in modern American life.