Mark Harmon on the Possibility of an 'NCIS' Return and New Book, ‘Ghosts of Honolulu’ (Exclusive)

‘NCIS’s Mark Harmon reflects on the 20th anniversary of 'NCIS' and dishes on his new book, ‘Ghosts of Honolulu: A Japanese Spy, A Japanese American Spy Hunter, and the Untold Story of Pearl Harbor.’ The book is available wherever books are sold.