Josiah Henson's 1849 autobiography inspired Harriet Beecher Stowe’s novel “Uncle Tom’s Cabin” and galvanized abolitionists. But for 30 years, he was enslaved here, on what was once a 270-acre plantation run by Isaac Riley. An acre of land and an old house are all that remain. Time Team America descends on a upscale DC suburb, digging for clues beneath the manicured lawn and peeling back layers of the old kitchen floor to tell the story of one of the most important Americans of the 19th century.