The Ending Of NCIS Season 4 Explained

The Season 4 finale of "NCIS," titled "Angel of Death," features the NCIS team fretting over a possible polygraph test from Homeland Security. This is perhaps the most appropriate symbolic image for this episode, as "Angel of Death" is a bundle of astonishing reveals, especially concerning Shepard. After Shepard returns home, she finds an empty glass and an open bottle of scotch in her study. Her mind immediately flashes to her supposedly deceased father, whose death is already thrown into question following the events of the previous episode, "Trojan Horse." The suspicious glass and bottle are run back to Abby Sciuto (Pauley Perrette) in the forensic lab for prints.

Still on the hunt for La Grenouille, Gibbs pushes Timothy McGee's (Sean Murray) hacking skills to gather more information on the arms dealer and his connection to the CIA. As McGee's cyberspace infiltration goes into the morning hours, Gibbs notices a picture of Shepard's father. We learn that he died 12 years ago — or maybe not? The possibility of Shepard's father still being alive becomes more real after the prints on the glass and bottle are matched to him, and this news really throws Shepard off. She is so emotionally invested in her father's death, the unraveling mystery, and the idea of revenge, that Shepard could become a threat to the team's investigation. This reveal also ties into the title, with death a main theme of the episode.

"Angel of Death" ends without us fully knowing if Shepard's father is indeed still alive, but it's not the only mystery the episode presents. Following a harrowing ordeal at the hospital involving heroin smugglers, DiNozzo and Jeanne make their way to a suspicious limo. As Jeanne confesses that she has a secret to share with DiNozzo, they're greeted by La Grenouille, who happens to be Jeanne's father. That's right. DiNozzo's love interest is related to the team's big season villain.