'NCIS': Gibbs Reveals Dark Secret From His Past

NCIS has shown us many sides to Leroy Jethro Gibbs through the years, but his team finding out about a dark moment in his past will change everything.

"...And Executioner" saw the NCIS team ace to find the person controlling a vigilante group being financed by a secret government bank account, only for them to stumble upon a game-changing truth about Gibbs (Mark Harmon).

The new episode immediately followed the events of last week's episode, "Judge, Jury..." also shedding light on the last-minute murder of their CIA ally. Returning to before his death, viewers saw as he was encountered by Leon Vance's (Rocky Carroll) ex-girlfriend telling him she wants back in on the mission.

Before he can shoot at her, she shoots him in the chest and kills him, leading to the cliffhanger last week where Leon and Gibbs found her next to the dead body.

The next morning the team investigates, while Gibbs and Vance continue to doubt Mallory's intentions. Elsewhere, Judge Milo (Mike Farrell) is quickly revealed as the mastermind behind the vigilante group when he holds a meeting of the judges involved to discuss an important case.

"Regarding the murder of Pedro Juan Hernandez, how does this counsel find the defendant Gunnery Sergent Leroy Jethro Gibbs?" Before all the judges find him guilty. The sentence for the crime? He reveals he has already ordered a hit on the beloved leader.

Fans of the show will remember Gibbs killed Hernandez to avenge the deaths of his wife Shannon Gibbs and their young daughter Kelly Gibbs. Gibbs reminisces on the murder when he finds a photo of Hernandez in his car after stopping at a diner, but he's interrupted after someone shoots at his truck.

The next morning, the team notices Gibbs is missing, but only Bishop (Emily Wickersham) has the bravery to check on him. As she calls her boss, he ignores the call as he takes one of the bullets out of his car and into evidence while standing in a field.

After one of the diner employees tells Bishop about the gunshots, the team gathers to figure out what happened but they hesitate to ask him. When he arrives, Gibbs seems to avoid the subject of what happened. The conversation is interrupted when Ducky (David McCallum) finds the connection tying Judge Deakin to the vigilante group.

Gibbs quickly goes and confronts the judge, telling him he knows he was the one who ordered the hit. Deakin pretends he is not aware of what Gibbs is talking about, but confronts him about murdering Hernandez.

In their battle of words, Milo tells Gibbs he is afraid to come clean to the team about murdering Hernandez, accusing him of being in the same team. After Gibbs says they are not the same he walks away, but Nick Torres (Wilmer Valderrama) sees him leaving the judge's bowling alley.

Bishop and Torres encourage McGee (Sean Murray) to ask Gibbs about what is happening with him, but when they approach him he walks away. The persistent agents don't give up and confront him in the elevator.

After some pressure, Gibbs comes clean about murdering "the man who killed my family," and how Deakin is trying to get him off the case by hanging the murder over him. The news leaves the rest of the team speechless, as Gibbs reprimands them for following him.

After the confrontation, Kasie (Diona Reasonover) uses the evidence Gibbs gathered from the shooting to find Mallory was the one who tried to kill him. Knowing she wouldn't have missed if she truly wanted to kill Gibbs, Mallory turns herself in for unexplained reasons. Vance confronts his ex about what happened and she reveals she lost everything and was forced to work for the judge.

A recorded conversation between her and the judge leads the team to finally arrest Milo. Despite the clean ending to the case, McGee, Bishop and Torres agree things are awkward after fining out about him killing Hernandez. However, they decide not to bring it up, at least for now.

Ahead of Tuesday's new episode, co-showrunner Steven Binder teased the reveal would cause serious change within the team.

"...it's going to change the whole team dynamic in a way," he told TVLine. "There will be this sort of fallout as the team reconciles this 'new Gibbs' that they didn't know existed."

Will NCIS recover from this recent twist? The show airs Tuesdays at 8 p.m. ET on CBS.