As of August 2015, "Castle" airs on ABC on Monday nights at 10/9c, with the Season 8 premiere scheduled to air September 21. TNT airs "Castle" reruns most weeknights.
"Castle" is a procedural drama television series starring Nathan Fillion and Stana Katic as a crime writer and a homicide detective who work together to solve crimes. The program begins its eighth season in 2015 on the ABC network. New episodes air on Monday evenings. As of August 2015, the first 5 seasons are in syndication, appearing on the TNT network and on local channels. TNT often runs "Castle" marathons on weekday afternoons and evenings.