'The Diplomat' Season 3 Recap: What To Remember Before Netflix's Political Thriller Returns

Published Oct 14, 2026, 2:12 PM EDT

Kendall Myers is a Senior Author with Collider. As part of the TV and Movies Features team, she writes about some of the most popular releases before, during, and after they premiere. In three years, she has written over 900 articles with topics ranging from classic sitcoms to fantasy epics.

The Diplomat has always been a complicated series, full of shocking twists and far-reaching conspiracies, but Season 3 is especially eventful. With marital problems, political betrayals, and secret plans, last year's new batch of episodes set up even more conflict for the impending Season 4. The show's latest installment moves Kate (Keri Russell) closer to the conspiracy's center, as she gets caught between the U.S. and UK governments.

'The Diplomat' Season 3 Takes the Wylers to the White House

After Season 2's cliffhanger ending, Season 3 begins with Grace Penn (Allison Janney) becoming President, which immediately intensifies Kate's situation. They rush to have her sworn in despite her distance from Washington, and Kate begins to consider taking the Vice President role. Since she was considered a replacement for Penn, she seems like the natural choice, despite the two women being at odds, and Kate is ready to accept the position — but Penn offers it to Hal (Rufus Sewell) instead. Though it disrupts their already unstable marriage, Hal takes the job, but Kate doesn't go with him. Unwilling to be reduced to the role of Second Lady, Kate keeps her position as ambassador, and they agree to have a secret divorce while publicly remaining married.

Yet, Hal cannot immediately become Vice President, and while he is vetted, Penn begins to doubt. He secretly makes deals to push for the Law of the Sea treaty, which several presidents have tried and failed to accomplish. Skeptical of his actions, Penn looks to other candidates until Kate tells her about Hal's ambitious plan. Impressed, Penn makes Hal the VP, moving the Wylers further up the political ladder. Unfortunately, even in London, Kate's influence is tied to her White House connection, making it more difficult for her to do her job.

Her inability to contact Hal, or get anything done without his backing, irritates Kate and drives the couple further apart, but Hal is more frustrated by their new arrangement. While the American public becomes obsessed with their relationship, Kate is ready to move on romantically. Though Dennison (David Gyasi) rejects Kate's advances, she eventually finds a lover, Callum Ellis (Aidan Turner), a British secret agent she works with. Meanwhile, President Penn's husband, Todd (Bradley Whitford), becomes convinced that Penn and Hal are having an affair, despite their denials. Kate and Hal's lives are tied together, and they must keep up appearances, which brings out their lingering feelings for each other.

'The Diplomat' Season 3 Highlights the Conspiracy that Started It All

Image via Netflix

While Hal's Vice Presidency opens up many storylines, the fallout from the carrier attack in Season 1 isn't over. Though the world blames Prime Minister Trowbridge's (Rory Kinnear) former colleague, Margaret Roylin (Celia Imrie), Penn is actually responsible, and her new Presidency makes it crucial that the truth stay secret. Roylin is one of the few people who know the truth. Luckily, she is under CIA protection, so Kate sends Hal to offer her amnesty. Instead, Roylin kills herself, which puts Eidra's (Ali Ahn) job at risk.

To save her career, Stuart (Ato Essandoh) suggests Eidra take the unwanted responsibility of evaluating Russian assets willing to work for the US, and she begrudgingly does. Though most of the intel is ridiculous, she hears from a former Lenkov colonel who knows the US ordered the attack. Though she dismisses it, Kate insists she investigate and eventually tells Eidra the truth. Fearing this report will reveal Penn's role, Kate, Hal, and Eidra meet with her. To prevent the fallout, Hal encourages Penn to come clean to Trowbridge. Penn is ready to do so, until Kate questions if Hal is trying to clear his path to the Presidency. In the end, Kate convinces Penn to tell only a partial truth and say that her predecessor, President Rayburn (Michael McKean), gave the order. This is a drastic step for Penn, who wanted to use her position to honor Rayburn, but she tells Trowbridge. Despite the agreed-upon secrecy, the Prime Minister announces Rayburn's supposed involvement to the world, destabilizing the relationship between the U.S. and UK.

'The Diplomat' Season 3 Ends with a Shocking Twist

Trowbridge's announcement makes Kate's position as ambassador more dangerous, yet she cannot avoid another crisis. Callum shares secret news of a Russian submarine off the UK's coast and urges Kate to discuss it with Trowbridge. But the Prime Minister has no interest in speaking with her. With an operational Poseidon nuclear torpedo attached to the submarine, Kate has to act, especially as Trowbridge seems to seek help from China. She calls in Penn and Hal, who arrange a summit with Trowbridge. When Trowbridge doesn't believe them, Penn orders underwater drone photos to prove the existence of the weapon, and Hal pushes Kate to suggest burying the missile in concrete, so no one gets the weapon. Trowbridge agrees, and the tense political situation is seemingly resolved. During this chaos, Kate realizes she still loves Hal and begs him to take her back.

However, the Season 3 finale delivers one more shocking twist when Callum privately confesses to Kate that he fears the Russians retrieved the weapon due to dropping radiation levels. When Kate shares the news with Hal, his reaction forces her to realize that he and Penn ordered the recovery and used the negotiations as a cover. The move risks war between Russia and the UK, making the story more dangerous than ever. As The Diplomat Season 4 picks up with the world on the brink of war and Kate now aware of the truth, Netflix's political thriller promises to be even more eventful.

The Diplomat Season 4 premieres October 15 on Netflix.