NCIS: Los Angeles is an American television series that premiered on CBS on September 22, 2009. The series is set in Los Angeles, California, and follows the stories of the members of the Office of Special Projects, an undercover division of the Naval Criminal Investigative Service. The show and its characters were introduced during the sixth season episodes of NCIS titled "Legend" and "Legend". These episodes served as a backdoor pilot for the series. The series' first season was originally planned to have thirteen episodes. On October 7, 2009, after rating as the most watched new show of the Fall 2009 U.S. television season, CBS ordered a full set of 22 episodes, which was extended to 24 episodes on November 4, 2009. Also, like the original NCIS show, the programme uses black and white images or rather proofs. However, instead of being just a three-second image, various black and white images demonstrating what will happen during the episode are displayed on screen. In the UK and Ireland, where NCIS: Los Angeles is shown, Sky have removed the images, presumably because they might cause seizures in people who have photosensitive epilepsy. This has since been expanded to the first four seasons of the show.