Everything We Know About The Diplomat Season 4

After an extremely painful year-long wait, The Diplomat returned for its third season in October 2025, allowing fans of the Netflix series to finally see which direction the story took after the extremely alarming way that Season 2 ended. And then, after eight gloriously twisty new episodes, Season 3 wrapped up with a flabbergasting cliffhanger of its own that's wilder than anything we'd seen on The Diplomat thus far. 

Fortunately for all of us, there was no need to wonder about whether The Diplomat will be back for Season 4, because Netflix already renewed series months before Season 3 dropped. It's the second time The Diplomat earned an early renewal, which is nice — you don't normally get to watch a new season of TV with complete confidence that the story will keep going in the future. Fans of The Diplomat have it good.

Let's take a look at what we know so far about Season 4 of The Diplomat. 

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The Diplomat Season 4 expected release date

Netflix has confirmed that Season 4 of The Diplomat will be a part of its release slate for 2026, which is about what we expected. That said, production on Season 4 started later in the year than production on Season 3 did, so it's possible that Season 4 won't hit in October like Seasons 2 and 3 did. 

Where The Diplomat Season 3 left off

Warning: This portion is full of spoilers for The Diplomat Season 3, including its ending.

Hal Wyler became vice president to Grace Penn — who gave Margaret Roylin the idea for the false flag attack on the HMS Courageous — so the Wylers' relationship was pretty much done. With Hal taking the slot that was supposed to go to Kate, and Kate then facing the possibility that her career is effectively over if she stays in Washington to be Second Lady, the love is gone. Kate returns to her ambassadorship in London, and Hal becomes an attack dog for the woman who had been the secret antagonist of Season 2. Grace admits that an American gave Roylin the idea, but claims it was the deceased President Rayburn who did it, rather than herself. British prime minister Nicol Trowbridge didn't respond well to that, and the U.K. and U.S. are having the same sort of breakup that Hal and Kate are.

Halfway through Season 3 we had a five-month time skip. Hal and Grace are BFFs now, and Kate is hooking up with a hot British spy who's got a line on a Russian nuclear sub that may have crashed at the bottom of the North Sea just off the coast of Great Britain with a nuclear superweapon among its cargo. Trowbridge, who doesn't trust Grace Penn at all, attempts to handle the situation without U.S. involvement — and Grace and Hal seize the moment by stealing the nuclear weapon under the guise of doing recon. Kate does the math and figures it out right at the end of Season 3: Callum knows the weapon is missing but not who took it, and we might be looking at a global war if anybody else realizes the weapon disappeared. That's a pretty intense place to leave things!

Read our full breakdown of the ending of The Diplomat Season 3.

The Diplomat Season 4 possible plot threads

"[Fans] should be worried. There's plenty to worry about," showrunner Debora Cahn told Netflix Tudum about the outlook coming out of Season 3. "It can be pretty chilling when you see who takes power and get the sense that they may be horrifically misusing it."  

Up to this point, Kate's loyalties have been very clear: She is here to advance American interests, even if American interests are being represented by the mastermind behind the attack on the HMS Courageous. That's just the side she's on — as Hal quips in the fifth episode of the third season, Kate was married to the U.S. government way before she ever met him. 

With Grace and Hal making such a troubling power move and then manipulating Kate into unwittingly help them pull it off, it may be that Kate's relationship with the U.S. could be evolving just as her relationship with Hal has. After all, the president and vice president are both pretty unhappy with her at the moment, and she's dating a British spy. Kate's understanding of the world is probably changing a lot during this situation. 

It'll likewise be interesting to see what Hal does next. Hal is not a good person — he's a political animal who will do anything for a win. But Kate's influence tempered him, especially when she was the one wearing the pants as ambassador while he was just the husband. But his new relationship with Grace is the opposite. She doesn't rein him in — she unleashes him. While Kate would have talked Hal out of stealing the nuclear weapon, Grace encourages his scheming if she thinks it will benefit her. But will Hal be able to recognize their toxic dynamic before it's too late? Or is he really The Diplomat's new baddie?

The Diplomat Season 4 cast and crew

Showrunner Debora Cahn will continue to be in charge, and every cast member is expected to return. Allison Janney and Bradley Whitford have been upped to series regular roles, so they'll be even more prominent in Season 4.

The Diplomat main cast:

• Keri Russell as Kate Wyler, U.S. ambassador to the U.K.
• Rufus Sewell as Hal Wyler
• David Gyasi as U.K. foreign minister Austin Dennison
• Ato Essandoh as Stuart Hayford, the ambassador's chief of staff
• Ali Ahn as Eidra Park, the local CIA station chief
• Rory Kinnear as U.K. prime minister Nicol Trowbridge
• Allison Janney as Grace Penn, the incoming U.S. president
• Bradley Whitford as Todd Penn, the new First Gentleman
• Aidan Turner as Callum Ellis

Where to watch The Diplomat

The Diplomat is exclusively available to stream on Netflix.