No, it’s not time for the Big Sleep. Or even to say Farewell, My Lovely, or a Long Goodbye. But Andrew Marlowe, master of detective fiction for ABC’s “Castle,” will turn over primary showrunning duties to exec producer David Amann for the upcoming season as Marlowe spends more time developing new projects for ABC Studios.

Marlowe, creator and exec producer of “Castle,” will still maintain a day-to-day presence on the show. “Castle” stars Nathan Fillion as a mystery novelist who overcomes writer’s block when he winds up partnering with an NYPD homicide detective (Stana Katic) to solve crimes.

“Castle” is a workhorse for ABC that has a passionate fan base. Amann has been on the show for the past four seasons. His previous credits include CBS’ “Without a Trace,” NBC’s “Crossing Jordan” and Fox’s “The X-Files.”

“David has proven himself to be a tremendous leader and a great steward of our show’s unique voice. I’m excited to continue our creative collaboration as he assumes his new responsibilities,“ Marlowe said.

“Castle” is coming off its most-watched season to date, with a 3.1 average in adults 18-49 in Nielsen’s live-plus-7 measure. In total viewers, it averages 14.3 million in live-plus-7.

Amann is repped by Jack Dytman at Gersh.