Underground Railroad: The Secret History

Underwater archaeologists search for the wreck of the USS Planter, a Civil War vessel seized by Freedom Seekers to escape the Confederacy; in Canada, experts use tech to uncover how Freedom Seekers lived once they made it to their new homeland.

Archaeologists uncover evidence of a Freedom Seeker community in the swampy marshlands between Virginia and North Carolina; in Maryland, experts investigate artifacts that may confirm the location of Harriet Tubman's childhood home.

Archaeologists unearth the lost community of Quindaro, Kan., a long-forgotten abolitionist town that shielded Freedom Seekers from bounty hunters; in Illinois, experts use tech tools to explore a secret underground tunnel.

Retracing the steps of freedom seekers escaping on the Underground Railroad, archaeologists use high tech to explore a Florida fort that was nearly erased from history.