Billy is returning to television joining the cast of the WGN show MANHATTAN for its second season.   He will play the character of Col Emmett Darrow.

From Deadline

Petersen will play Col. Emmett Darrow, the enigmatic new ranking military officer at Los Alamos. A deeply religious and patriotic man, Darrow feels called by God to usher in the atomic future and to spread American values across the globe.

Manhattan on IMDB