Tom's next guest today is the author of a fascinating new biography of Harriet Tubman, the famed 19th century anti-slavery activist, whose remarkable life story is also the subject of Harriet, the new film by director Kasi Lemmons that's hitting US screens today.Erica Armstrong Dunbar is a professor of history at Rutgers University. Her fascinating new Tubman biography is called She Came to Slay, and it's being published this month by Simon and Schuster.Professor Dunbar will be talking about the new book this Sunday at 1pm at the Brilliant Baltimore Festival, which combines the Baltimore Book Festival and City Lights. For details on her event, click here.Erica Dunbar joins us on the line from the studios of WHYY in Philadelphia.