“NCIS” Season 21 is set to premiere on Monday, February 12, 2024, at 9 p.m. ET on CBS. The show was renewed for another season, and fans can expect changes in the cast, with the departure of David McCallum as Donald “Ducky” Mallard. The season 20 finale left a major cliffhanger involving Torres, and viewers are eager to see how it unfolds. The cast includes Sean Murray, Wilmer Valderrama, Katrina Law, Gary Cole, Brian Dietzen, Diona Reasonover, and Rocky Carroll. You can watch the new episodes on CBS or stream on Paramount+. The show will retain its Monday night slot at 9 p.m. ET.