Kelsey Grammer is taking a dark turn in his first drama series, Starz’s upcoming Boss, in which he stars as the ruthless mayor of Chicago who is diagnosed with a degenerative mental condition that only he and his doctor know about. The series, which premieres Oct. 21, marks Grammer’s return to television after a two-year break. “I took a break for a while, and there were a lot of reasons I did,” he said. “I decided I needed to make a life change.” As for the genre change from comedy to drama, it may have something to do with his experience on his most recent half-hour series, the short-lived ABC sitcom Hank. “Nobody really liked that,” Grammer said. “It wasn’t really funny.” Grammer even called Warner Bros. TV president Peter Roth. “I asked, ‘How do we put a bullet in this thing?’ ” The experience has been completely different on Boss. “It’s been probably the greatest time of my life, creatively,” Grammer said. “I have said some of the most extraordinary language I’ve said in my life doing this role.” Here is a trailer for the series, written by Farhad Safinia and directed by Gus Van Sant: