NCIS Hawaii star Vanessa Lachey, who plays Special Agent Jane Tennant, the first woman in charge of the NCIS Hawaii Field Office at Naval Base Pearl Harbor, was so excited, she posted the following on Instagram: “I wanted to tell you about our season premiere – Sept. 19. We have a very, very special guest. I am very excited. I can’t tell you who it is. We actually had an email last night saying we weren’t allowed to mention who it is because they want to keep it a secret. But I can say that all the NCIS OG fans won’t be disappointed. We are bringing back a fan favorite, actually two fan favorites, coming here to the island to kick off the season, Special guests. Top secret. You guys are going to love it. It’s going to be a massive 2-hour premiere!” It begins on NCIS with “A Family Matter” episode that picks up from the cliffhanger season 19 finale, with Special Agent Alden Parker (Gary Cole) still on the run with his ex-wife Vivian (Terri Polo), as the team investigates who from his past might have a personal vendetta against him in hopes of clearing Parker’s name. Luckily, the D.C. team is able to enlist the help of Tennant and computer specialist Ernie Malick (Jason Antoon), who are in town meeting with director Leon Vance (Rocky Carroll) in preparation for a global military exercise. Together, they track down their prime suspect, The Raven. CBS Studios just posted this fun Instagram. Send in your answer. Then in the 10 o’clock hour, in the “Prisoners’ Dilemma” episode, Tennant’s team, along with NCIS agents Nick Torres (Wilmer Valderrama) and Jessica Knight (Katrina Law), track The Raven’s whereabouts to the island of Oahu and learn about his plans to attack RIMPAC (The Rim of the Pacific Exercises), the world’s largest international maritime warfare exercise, on the exciting conclusion to the special crossover event. NCIS and NCIS: Hawaii air on Monday nights on CBS at 9 p.m. and 10 p.m. ET/PT respectively. Next, Everything We Know So Far About NCIS Season 20