CBS declares Monday, Sept. 25 "NCIS Day" in honor of the 20th anniversary and devoted fans of broadcast TV's #1 show. The celebratory day falls 20 years and two days after the Sept. 23, 2003 launch of this powerhouse series, which has aired 459 episodes to date and sparked a global franchise. With all five NCIS series combined, the franchise will reach a milestone 1,000th episode during NCIS' upcoming 21st season.

Festivities will include:

• A mini NCIS marathon (from 8:00 to 11:00 PM on the CBS Television Network with streaming available on Paramount+*), featuring the original cast from the first-ever NCIS episode, the second season finale, and a key episode from season 19 with the series' current cast. See loglines below.

• An opportunity for fans to take 20% off NCIS merchandise with code NCIS20 at checkout in the NCIS storefront of ParamountShop.com from Sept. 7 through Oct. 2. There will also be an on-air QR/discount code displayed periodically throughout the NCIS marathon so fans can scan and shop.

• The launch of a new joint @NCISverse handle across all of CBS' NCIS franchise's social media platforms to engage the shows' fans with a more immersive experience!

• The debut of the Network's own social take on the show's Bandium app, which Gary Cole's Special Agent Alden Parker introduced to the NCIS team during season 19 to "revolutionize" how the team shares information and gets case alerts and updates. CBS' version of "Bandium," accessed through an opt-in messenger feature on Instagram and Facebook, will enable "special agent fans at home" to receive exclusive content, personalized shareable content, special announcements and more!

• Beginning Monday, Sept. 18, fans can log in to their Meta accounts (Facebook https://www.facebook.com/NCISverse or Instagram https://www.instagram.com/NCISverse) for early opt-in access to "Bandium." Those who opt-in before the mini marathon will receive a special message and a "first look" trailer on "NCIS Day" for the new series NCIS: SYDNEY (which debuts Monday, Nov. 13 on CBS). *

• Sneak peeks at the newest - and first international - installment of the franchise, NCIS: SYDNEY, during the on-air marathon and via CBS' social extension of "Bandium."

Loglines for the "NCIS Day" mini-marathon episodes, airing Monday, Sept. 25 on CBS and available to stream on Paramount+*, follow:

8:00-9:00 PM, ET/PT

NCIS Season One Premiere Episode (OAD: 9/23/2003)

"Yankee White" - In the series' premiere episode, NCIS (Naval Criminal Investigative Service) Special Agents Gibbs (Mark Harmon) and Tony DiNozzo (Michael Weatherly) and NCIS medical examiner Dr. "Ducky" Mallard (David McCallum) arrive on Air Force One to investigate what initially appears to be a death by natural causes. But their investigation is hampered by inter-agency squabbles with the FBI and Secret Service, each believing that they should be the primary investigating unit. Gibbs cunningly gets control of the case from the others, but still has to go head-to-head with Secret Service Agent Kate Todd (Sasha Alexander)*, who insists she remain on the case. As the investigation continues, the sudden death of another Marine officer with the same job as the first victim convinces Gibbs and Todd that they are dealing with a terrorist plot against the president - and the killer is getting closer. (*Alexander was a series regular in this series premiere episode of NCIS, becoming an NCIS special agent by the episode's end.) Executive producer Donald P. Bellisario both directed the episode and wrote the script.

9:00-10:00 PM, ET/PT

NCIS Second Season Finale Episode (OAD: 5/10/2005)

"SWAK" - When a letter sealed with a kiss is delivered to NCIS, Tony (Michael Weatherly) assumes it's for him and opens it, only to release a mysterious powder into the NCIS squad room. Gibbs (Mark Harmon) and the team are forced into quarantine in the NCIS autopsy room pending the results of tests to identify the strange powder. As Abby (Pauley Perrette) discovers the substance is a genetically altered version of the plague, Tony and Kate (Sasha Alexander) are placed in a bio-hazard isolation ward for fear of exposure. In the clear of the deadly virus, Gibbs and McGee (Sean Murray) race to track down the sender before the deadly plague destroys one of their team members. Steven Eckholdt guest stars as the doctor who treats the infected NCIS agent; Mariette Hartley guest stars as a potential suspect. Dennis Smith directed the episode from a script by executive producer Donald P. Bellisario.

10:00-11:00 PM, ET/PT

NCIS Season 19 Episode (OAD: 1/17/2022)

"All Hands" - After a civilian research vessel in the North Atlantic picks up a small boat of wounded Navy officers, Special Agent Parker (Gary Cole) and his NCIS team arrive on the ship and are forced to hide after discovering terrorists on board. Also, Special Agent Knight (Katrina Law) takes a paper doll with her on the mission to capture photos for her niece's grade school class. Martha Mitchell directed the episode from a script written by Christopher J. Waild.

NCIS has been a top 20 series for 18 of its 20 seasons and has been television's top broadcast drama for the last five consecutive seasons - and 13 of the last 14.

NCIS, now in its 20th season in the U.S., is one of the biggest global franchises across all of entertainment. The NCIS franchise has been viewed for over 4 trillion minutes over 20 years in the U.S. - that would be 228 telecasts per American. It's available in 200 markets in more than 60 languages and CBS has produced three spinoff series, NCIS: LOS ANGELES, NCIS: NEW ORLEANS and NCIS: HAWAI'I. In 2023, the first international spin-off, new series NCIS: SYDNEY, will premiere Monday, Nov. 13 (10:00 PM, ET/PT) on the CBS Television Network, and streaming on Paramount+ (live and on demand for Paramount+ with SHOWTIME subscribers, or on demand for Paramount+ Essential subscribers the day after the episode airs)*.

NCIS stars Sean Murray as Special Agent Timothy McGee, Wilmer Valderrama as Special Agent Nickolas "Nick" Torres, Katrina Law as Special Agent Jessica Knight, Brian Dietzen as Dr. Jimmy Palmer, Diona Reasonover as forensic scientist Kasie Hines, with Rocky Carroll as NCIS Director Leon Vance and Gary Cole as NCIS Special Agent Alden Parker. The series is executive produced by Steven D. Binder, David North, Chas. Floyd Johnson, Mark Harmon, Scott Williams, Chris Waild and created by Donald P. Bellisario. NCIS is produced by CBS Studios in association with Belisarius Productions.

*Paramount+ with SHOWTIME subscribers will have access to stream live via the live feed of their local CBS affiliate on the service, as well as on demand. Paramount+ Essential subscribers will not have the option to stream live, but will have access to on-demand the day after the episode airs.