NCIS said a tearful goodbye to series stalwart Abby Sciuto on Tuesday, May 8. Actress Pauley Perrette made her final appearance as the goth scientist.

The Toughest Chick In Town

After 15 seasons, the hit crime show bid farewell to Abby, with the explosive episode kicking off with her in critical condition, following a violent encounter. Meanwhile, poor Clay didn't make it.

Flashbacks were peppered throughout, one of which included a surprise cameo from Michael Weatherly's Tony DiNozzo, who left in season 13.

Although Abby was in trouble, her team did not give up on her.

"This is the indomitable Abby Sciuto we're talking about. I don't care what the odds are. You never count her out," pointed out Palmer.

It soon became clear that the mugging, which left Abby in hospital, wasn't a random act of violence, either, but a hit on her life.

Thankfully, she came around halfway through the episode, leading to a sweet moment where McGee had to fix her hair into pigtails since Abby couldn't manage it with her arm in a sling.

Once it was revealed that the man behind the attempt on Abby's life was none other than season 6's Marine Sergeant Robert King, the tough-as-nails lady confronted him herself.

She slipped cyanide in his coffee while rattling off the names of all the women who had perished while horrible people like him get to live.

Time To Say Goodbye

She then convinced King to confess to killing Clay to save his life, which led to the big reveal that Abby will be leaving the team for good.

"I'm not coming back. I'm leaving NCIS. Clay died saving my life and I owe him a debt and I tend to see that through. Clay always wanted to start a charity in honor of his mom and since he's not here to make that happen, I will. ... It wasn't an easy decision. You guys are my family and this is my home, but you have to go with your gut and my gut is telling me that I have to go," she explained.

When McGee admitted he couldn't say goodbye to her, Abby promised him it wasn't goodbye for good, just for now. She then left a note for Mark Harmon's character, Gibbs, rather than saying goodbye to him face to face.

After reading the note, Gibbs looked out the window, only to find Abby standing there. He signed that he loved her. She then packed up her things in the lab, leading to some of the most emotional scenes of the entire episode.

Before the episode aired, Perrette took to Twitter to share how worried she was that fans wouldn't like her final episode as Abby. She tweeted that she had done some of her best work on this episode and that she hoped fans would be happy with the final product.

The Real Reason For Leaving

Rumors have swirled for months that Perrette was leaving the show due to ongoing difficulties with CBS, the show-runners, and, her co-star Harmon.

Allegedly, Perrette, a vocal dog lover, had an issue with the rescue pitbull that Harmon continuously brought to set. The dog even attacked a crew member, requiring him to get 16 stitches, but the incident was played down as roughhousing.

Perrette reportedly made her feelings clear, but bosses sided with Harmon, who is also a producer on the show.

A Tweet, sent around October of last year, was Perrette's attempt to squash such stories, but it's worth noting the timeline for when she made the decision would fit.

The manner in which Abby said goodbye to Gibbs would also chime with this, as the two weren't required to share any screen time.

NCIS airs Tuesdays at 8 p.m. on CBS.