Spoilers ahead for the Season 18 finale of NCIS on CBS, called "Rule 91."

NCIS has a long history of ending season finales on killer cliffhangers, and the stakes were already sky-high for "Rule 91" before the episode ended on a twist that was quite literally explosive. Between how the Season 18 finale handled Bishop's story after being accused of leaking NSA documents and what happened to Gibbs' boat in the final moments, it's hard not to wonder if NCIS' original plan was to say goodbye to two major characters before the Season 19 renewal and guarantee of more Mark Harmon.

In fact, NCIS did say goodbye to one major character. The episode revealed that the preview for "Rule 91" wasn't a bait-and-switch, and Season 18 really was sending off Emily Wickersham's Eleanor Bishop, who had joined the series all the way back in Season 11. Bishop more or less framed herself for espionage by confessing to leaking NSA documents, when in reality Odette had planted them to set up a way for Bishop to leave NCIS in disgrace and move on for an undercover op that she'd been secretly training for.

Although the episode didn't come out and confirm that Emily Wickersham won't be back for Season 19, nobody at NCIS other than Torres knows that Bishop and Odette planned the whole thing with the NSA documents to set up her departure. So, her name isn't cleared with anybody else that she could just return to business as usual at NCIS, and the op for Odette didn't exactly seem like something that Bishop could start and finish in just a couple of months.

And "Rule 91" really felt like a goodbye for Bishop. She got a final conversation with McGee, a supportive pep talk from Gibbs, and an emotional farewell to Torres that involved Torres demanding answers and Bishop finally planting a kiss on him, seemingly proving that their "talk" not so long ago didn't actually lead to a secret romance. The boxes were all ticked for "Rule 91" to serve as her big departure, at least for now, and the stage had been set throughout Season 18 to indicate that this twist has been a long time in the making.

It was the Gibbs twist that left me wondering if the NCIS team was originally planning to say goodbye to Mark Harmon's character as well. Gibbs was driving his latest boat, which he named Rule 91, across the water, looking so content that it was inevitable that something was going to go horribly wrong. And something did indeed go wrong, as his happy boat ride was came to an explosive conclusion when the vessel blew up, sending Gibbs flying into the water.

Gibbs did begin to swim after landing in the water, so he's definitely not dead, but NCIS could have easily used this as a way to write out Mark Harmon and set up Season 19 if the show had scored a renewal but lost Gibbs in the process. Killing off Gibbs would have been a hell of a twist, and the explosion of the boat was so destructive that I still have no idea how he was thrown free before being burned to death or blown to bits just like the Rule 91.

Even knowing that Mark Harmon was slated to return for Season 19, I had a thrilling moment of wondering if NCIS had thrown in a twist for all of those who had gotten comfortable with the idea of Gibbs returning. In fact, I feel kind of cheated that NCIS was so thorough in blowing up the boat but didn't use it to kill him off. Not that I want NCIS to lose Mark Harmon after nearly two decades, but I might spend the whole hiatus wondering how exactly Gibbs survived.

So, NCIS really could have used this ending to kill off Gibbs if plans to bring him back for Season 19 had fallen through and Mark Harmon wouldn't return, and I really would have been okay with it. As it stands, the attempt to kill Gibbs set up a major plot to start the next season.

It's presumably tied to the serial killer case Gibbs has been working with Marcie (played by Mark Harmon's real-life wife Pam Dawber), which got more complicated this week with Gibbs discovering bugs planted to listen in on their investigation. Still, only time will tell how NCIS will delve into what happened to Gibbs, and how the unit will move on without Bishop.

NCIS will return to CBS with Season 19 in the fall, complete with Mark Harmon back as Gibbs despite a lot of uncertainty surrounding the character in the second half of Season 18. Katrina Law may or may not be on board as Jessica Knight, and how much Gibbs will be involved remains to be seen, but at least the show will be back.

Plus, the NCIS franchise is adding a new Hawaii-set show, so it won't be getting any smaller even despite the cancellation of NCIS: New Orleans. And there are plenty of viewing options in the meantime over the summer during the wait for NCIS to come back, so the current finale season isn't the end of TV options in the coming weeks.

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