'The Diplomat' Season 4 Ending, Explained: Breaking Down the Shocking Cliffhanger

Her hair might be a bit less frizzy since becoming Second Lady, but Kate Wyler (Keri Russell) is back, and statecraft has never been so chaotic. The Diplomat season 4 premiered on Netflix on October 15, and it had everything—an assassination plot, a fiery resignation, and a political upheaval so shocking, it’ll have you begging for a season 5. Before we get into what the end of The Diplomat season 4 means, we have to review where The Diplomat season 3 left off.

After a brief separation, Kate and Hal (Rufus Sewell) are officially back together, with Kate determined to work on their marriage despite her job as the U.S. Ambassador to the U.K. and his job as the Vice President of the United States. Unfortunately, the couple could barely bask in the glow of their renewed relationship when, in the season 3 finale, Kate discovered that Hal had conspired with President Grace Penn (Allison Janney) to steal the Poseidon, a nuclear weapon made by the Russians and found off the coast of the U.K. They did this without telling their closest ally, who thinks the weapon is still there and believes that the U.S. will work with them to bury it at the bottom of the ocean. When season 4 picks back up, Kate—who went above and beyond to get the capricious Prime Minister Nicol Trowbridge (Rory Kinnear) to agree to work with the US on the Poseidon—is still reeling from the betrayal. More than that, she’s struggling to figure out how to keep her husband's actions from the U.K. government and the Russians, who are determined to recoup their deadly technology.

As Kate’s increasingly ruthless political instincts and loyalty to Hal continue to butt up against her morality, she regularly turns to her ever-reliable deputy, Stuart Heyford (Ato Essandoh), and the London CIA office chief, Eidra Park (Ali Ahn), for guidance. But when President Penn becomes erratic in the wake of trauma, Kate finds herself on the precipice of potentially overthrowing the Penn administration. Desperate for all the details? Read on to find out how The Diplomat season 4 ends, and what it means for a potential season 5.

A Thorough Recap of 'The Diplomat' Season 4, From the Surprise Cast Shake-Ups to the Ending Cliffhanger

Who shot the President in 'The Diplomat' season 4?

When President Penn was shot at the end of episode 1, “Windsor,” it was unclear whether this rogue act of terrorism was motivated by the death of the British soldiers in season 1—a tragedy put into motion by the American government—or by the President’s decision to steal Russian nuclear technology from right under the U.K. Prime Minister’s nose. And while it turned out to be the former—U.K. intelligence informs the President that she was shot by a rogue soldier who was later found dead—the resolution of this particular plot point feels suspiciously thin. Although it may be that her shooting was the act of a lone wolf, it feels a bit anticlimactic.

What happened to Austin Dennison in 'The Diplomat' season 4?

In a shocking turn of events, Austin Dennison (David Gyasi), the U.K. Foreign Secretary, was killed off in season 4 of The Diplomat. He died in a helicopter crash while working for the Trowbridge administration, and the loss hits Kate hard. Not only did the two have a flirty relationship in seasons 1 and 2, but Dennison was often the only person Kate could trust to keep Trowbridge from doing something reckless, like, say, outing the fact that the U.S. government had betrayed the U.K. again.

What happened to Nicol Trowbridge in 'The Diplomat' season 4?

After three seasons of watching the U.K. Prime Minister Nicol Trowbridge bluster his way through diplomacy with the U.S., The Diplomat finally said goodbye to the character. Trowbridge stepped down midseason in dramatic fashion, not-so-subtly calling out President Penn and the U.S. as dangerous to the U.K. in his resignation speech. He left his post after a particularly harsh move from Kate, who reminded him that they had footage of him attempting to strangle Margaret Roylin in front of the new Foreign Secretary. The threat was an effort to keep him quiet about the Poseidon nuclear weapon, which Hal previously revealed the U.S. had stolen.

Who is the new Prime Minister in 'The Diplomat' season 4?

Doctor Who and Broadchurch alum Jodie Whittaker made her debut on The Diplomat season 4 playing Bethan Vaughan, the new no-nonsense (and non-Nazi) Prime Minister of the U.K. Though Kate originally hopes that Bethan will be an enthusiastic partner with the U.S., she very quickly learns that Bethan has no interest in partnering with the Americans. She knows that they took the Poseidon, leaving the U.K. vulnerable to potential retaliation from Russia, which she believes will blame the U.K. for their missing nuclear weapon. So, she decides to let Russian forces into U.K. waters to “collect their dead”. She hopes that, when they realize their nuke is gone, they’ll have the good sense to realize that the U.K. had nothing to do with it; otherwise, the country never would have invited the Russians in.

Is Kate still the Ambassador to the U.K. in 'The Diplomat' season 4?

As if Kate didn’t have enough on her plate this season, she’s been given a new job: Babysitter to the First Gentleman. Unhappy with his marriage and desperate for a change, Todd Penn (Bradley Whitford) decides to join Kate in London as a Special Envoy. Kate originally hopes to use Todd Penn to her advantage with the President, but Todd is loyal to his wife when President Penn tells Kate to inform Prime Minister Vaughan that, should she not rescind her invitation to the Russians, the US is prepared to send in warships to protect the Russian submarine.

After confiding in Stuart and Eidra, Kate decides to try some diplomacy instead and offers Vaughan an alternative: Collect the dead and deliver them to the Russians, taking away their excuse to come poking around. She also neglects to tell Vaughan about the President’s threat. Unfortunately, PM Vaughan is not convinced, and when the President discovers Kate went against her orders, she fires her and unofficially replaces her with Todd, making it clear that this will be Kate’s final week as the Ambassador.

What happened to Stuart in 'The Diplomat' season 4?

The Diplomat season 4 ends with Kate leading an apparent revolt against President Penn, but it’s Stuart who actually inspires the charge. Before the G7, Kate looped Stuart in on what President Penn had done with the Poseidon. When it looked like Penn wasn’t backing down from her plan to send U.S. warships into allied territory, he drafted and sent a dissent channel cable, hoping to at least get his opposition to the idea on the record. After getting wind of the dissent cable, Penn has Stuart reassigned—an act of retaliation that could end Stuart’s career and his relationship with Eidra.

What happened at the end of 'The Diplomat' season 4?

After Todd delivers the President’s threat, PM Vaughan goes on the attack at the G7 Summit, preparing to move to strip the U.S. of its position. She informs Kate she will offer Russia a British military escort, and notes that, should U.S. warships fire on U.K. forces, it will cause a domino effect that could lead to the U.S. losing its world standing—not to mention the risk of sparking WWIII.

Vaughan plans to expose Penn at the G7, but before she can take the floor, Penn beats her to it. She tells the G7 that the U.S. has come into possession of the Poseidon and would be sending warships to the U.K., framing it as a gift of protection to the allied nation—and making it clear that the U.S. would fire upon allied ships, should they try to get past them. This is the final straw for Kate, who walks out of the meeting, leaving her badge, and potentially her career and marriage, behind.

The Diplomat season 4 ends on a massive cliffhanger, with Kate—followed by Chief of Staff Billie Appiah (Nana Mensah), Secretary of State Miguel Ganon (Miguel Sandoval), and Hal—publicly resigning from the Penn administration and walking out of the G7. Reporters gathered at the gate outside the event as Kate set the stage for Hal to deliver a message from “the Vice President of the United States.”

Are Kate and Hal still together after 'The Diplomat' season 4?

Throughout season 4, Kate assures Hal that she is committed to working on their marriage, but her decision to go against the President leaves Hal shaken, especially after she uses his guilt over their strained marriage to convince him to pitch her idea of retrieving Russia’s dead to President Penn. This manipulation is a bridge too far for Hal, and he makes it clear that, after this G7 Summit, their marriage might be done for good. Before Kate’s dramatic resignation, she kisses Hal and tells him she loves him, clearly hoping that her actions won’t hurt his position as Vice President and seemingly accepting the end of their marriage. Hal, of course, ends up following her lead, which could mean there’s hope for the couple after all.

Will there be a season 5 of 'The Diplomat?'

The Diplomat has yet to be officially renewed for season 5, but given the cliffhanger ending, it seems unlikely the show will end here.

A potential season 5 would certainly have a lot to work with. Though it’s unclear what Hal and Kate’s next move is, I’m guessing it has something to do with the 25th Amendment—something that has often been discussed during the Trump Presidency.

If invoked with the support of a majority of the Cabinet, the 25th Amendment gives the Vice President and a majority of the Cabinet the right to transfer the powers of the President to the Vice President. Given that Hal already has the support of Ganon, and the hints dropped previously in the season that the rest of the Cabinet has been uneasy with President Penn, it seems likely that this is what they have in mind. Not only would this be brand new territory for the show and the fictional United States, it would also present a whole new set of challenges for Kate and Hal moving forward. If President Penn is impeached or, essentially, dismissed from the presidency, does Hal become president? Can Kate be the First Lady and an ambassador, or will The Diplomat get a makeover for the yet-to-be-confirmed season 5?