Source: Entertainment Weekly

Keri Russell struggles to keep her head above choppy foreign waters on Netflix’s The Diplomat.

The actress, who previously starred on the incendiary thriller The Americans, has received two Emmy nominations for her performance as Kate Wyler, a U.S. ambassador attempting to maintain the partnership between the U.S. and the U.K. amid political strife, scandal, and international crises.

Kate has long been primed to clinch the vice presidency, but is forced to reckon with the death of the U.S. president at the end of season 2, which was more or less caused by her scheming husband, Hal (Rufus Sewell). Season 3’s twists saw unexpected characters ascend to power, while a potential “doomsday weapon” took center stage.

It all ends on a heck of a cliffhanger, and it would be downright cruel to deny fans more story. So, will there be a season 4 of The Diplomat? Here’s what we know.

Yes, The Diplomat was renewed by Netflix months before the season 3 premiere.

“I’m so excited about Season 4,” creator and showrunner Debora Cahn told Netflix’s Tudum. “It’s going to be a lot of fun. We get to the end of a season and I always think, ‘Well, there’s no way that we can do this again.’ And then we dig back into it, and it’s like, ‘Oh my God, we have to keep going.'”

Hal spent the first two seasons of The Diplomat angling for Kate to become vice president. But after Grace Penn (Allison Janney) is appointed POTUS following the death of President Rayburn (Michael McKean), she chooses Hal as her right hand.

What follows is a potential nuclear disaster due to a Russian submarine off the northeast coast of England carrying a torpedo called “Poseidon,” which multiple characters describe as a “doomsday weapon.” As Kate works with U.S. and U.K. officials to find an agreeable solution for dealing with the submarine, Grace and Hal are secretly hatching their own plan.

Hal tells Kate to present the U.K. government with a “Runit Dome” solution, essentially creating a concrete shell to corral the radioactivity leeching off the submarine. But when the sub is found and the Poseidon is missing, she realizes she may have been played.

Did Grace and Hal plot to steal the Poseidon? If so, what impact will that have on the relationship between the U.S. and the U.K.? The season ends with those questions ringing in Kate’s ears.

While there’s no official plot synopsis for The Diplomat season 4 yet, Cahn spoke with Collider about how keen she and the writers are to explore the complex dynamics between Kate, Grace, and Hal.

“What does it mean to have two powerful women with one powerful man stuck in the middle of them?” the showrunner posited. “How do those relationships impact each other and change each other?”

She elaborated, “Hal is in a different relationship right now. He has a very, very potent and important relationship developing and succeeding with another woman who happens to be the President of the United States. The idea that that was not going to change the chemistry of the marriage was also magical thinking.”

But there are also geopolitical concerns. Speaking with Tudum, Cahn said fans “should be worried,” adding, “It can be pretty chilling when you see who takes power and get the sense that they may be horrifically misusing it.”

Who’s in The Diplomat season 4 cast?

The biggest piece of season 4 casting news to emerge is that Janney will be promoted to a series regular alongside Bradley Whitford, who plays Todd Penn, Grace’s husband.

Ahead of season 3, Cahn spoke with Entertainment Weekly about the pairing of Janney and Whitford, who previously acted opposite each other on The West Wing.

“I got more confident that we could have the two of them in the same place and it would feel like something new,” Cahn told EW. “And giving them a relationship that’s so different than the one that they’ve played in the past is really great. What’s been most gratifying for me is that you become exposed to Grace Penn as a three-dimensional person.”

The Diplomat season 4 does not have an official release date as of this writing. But What’s on Netflix reports that filming for the season begins on Nov. 3, 2025.

Season 3 was filmed in 2024 and released in the fall of 2025, so there’s a good chance that season 4 will premiere in the fall of 2026.

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