Cole (Alden Parker) makes his debut in episode 2 and joins the main cast in episode 3. Mark Harmon (Leroy Jethro Gibbs) departed the show in episode 4 "Great Wide Open", but remains on the title sequence for the remainder of the season, but was removed in season 20. Episode 17 begins a crossover event that concludes on NCIS: Hawaiʻi season 1 episode 18. Season 20 (2022–23) Episode 1 begins a crossover event that concludes on NCIS: Hawaiʻi season 2 episode 1. Episode 10 begins a crossover event that continues on NCIS: Hawaiʻi season 2 episode 10 and concludes on NCIS: Los Angeles season 14 episode 10. Home media References General references that apply to most episodes External links NCIS NCIS