First, he had to tell his team that he killed the man who killed his wife and daughter when a vigilante network targeted him for the crime. Then, he struggled with the aftermath of that confession, possibly more than McGee (Sean Murray), Bishop (Emily Wickersham) and Torres (Wilmer Valderrama) did hearing it. Any sleepless nights for them can't compare to Gibbs unraveling to the point that he considered turning himself in to the police.
And now, one of his dead wives, Diane (Melinda McGraw), is back in his life somehow, as seen in the Season 16 finale trailer.
The end of the penultimate episode of the season set up the events of "Daughters." Just as Gibbs was about to leave the office, Vance (Rocky Carroll) stopped him. "It's Fornell," the NCIS Director told him. "You need to get to Mercy Point Hospital. Fast."
But Fornell's (Joe Spano) not the one who's been admitted. His and Diane's daughter, Emily (Juliette Angelo), is, after an opiate overdose. (Fornell was also married to Diane, and the two had reconciled prior to her death.)
Fornell pleads with Gibbs to do whatever is necessary to take down drug dealers and suppliers in the area. As a result, Gibbs is haunted by the personal aspects of the case and his history with vigilante justice.
Diane can't be alive since she was shot in the head (as the trailer helpfully reminds us), but with Fornell unraveling, Gibbs could use a familiar face. As Diane herself points out, what Gibbs needs to ask himself is, "What's happening?"
NCIS, Season 16 Finale, Tuesday, 8/7c, CBS