A mini Boardwalk Empire reunion is taking shape on the new TV mini-series Waco.

Based on the true story of the siege of a religious cult in Waco, Texas in 1993, new additions to the cast include former Boardwalk stalwarts Shea Whigham and Paul Sparks. They will join the already cast Michael Shannon – who plays the lead FBI negotiator – on the six part mini-series, which will premiere next year.

Whigham will play the FBI agency’s tactical commander, while Sparks will take on the role of a troubled confidante of cult leader David Koresh (to be played by Taylor Kitsch).

Also on board for Waco are British star Andrea Riseborough, who will play Sparks’ wife, John Leguizamo as an ATF agent and Rory Culkin, a musician who becomes a true Koresh believer.

Waco has been written by Drew and John Erick Dowdle (No Escape), with the latter serving as director.