Actor Mykelti Williamson arrives for the party to celebrate the one year anniversary of The WIGS Digital Channel at Akasha on May 2, 2013 in Culver City, California

Actor Mykelti Williamson arrives for the party to celebrate the one year anniversary of The WIGS Digital Channel at Akasha on May 2, 2013 in Culver City, California

*Mykelti Williamson and Devon Gummersall have been cast in “Underground,” WGN America’s pre-Civil War series about the Underground Railroad.

The series from Sony Pictures TV and Tribune Studios follows a group of slaves planning an escape from a Georgia plantation, crossing 600 miles toward freedom. They are aided along the way by a secret abolitionist couple running a station on the Underground Railroad, as they evade those tasked with bringing them back — dead or alive.

Williamson, currently recurring on FX’s “Justified,” will recur on Underground as Moses, a fiery preacher for the slaves on the plantation who decides to take his family on the run.

Gummersall, currently on AMC’s “Mad Men,” is set to play the series regular role of John Hawkes, a lawyer and abolitionist who is trying to reconcile the way things are with the way things should be.