In the trailer for The Diplomat’s fourth season — out on Oct. 15 — Kate Wyler (Keri Russell) furiously accuses the Penn administration of crossing a line. White House Chief of Staff Billie Appiah (Nana Mensah) responds unblinkingly, “The line moves.”
As we wait to find out how, exactly, Kate will work to contain President Grace Penn (Allison Janney) and Vice President Hal Wyler’s (Rufus Sewell) latest bombastic move, let’s hit the rewind button.
Last time we saw Kate, she had come to the realization that Russia’s deadliest weapon had been secretly snatched by the United States, a decision that could cause terrifying ripple effects at home and abroad.
“That would make a lot of people really angry: both Russia, who made the weapon, and the UK,” says creator, showrunner, and executive producer Debora Cahn. “Hal and Grace are playing with matches in somebody else’s house. The repercussions are not going to only land on America — they’re going to land on another country.”
Keep reading to brush up on all the major Season 3 moments you need to remember before The Diplomat returns.
While Kate was initially the top choice for VP, it’s Hal who President Penn picks to be her second in command. In a dramatic twist, the ambassador decides not to board the plane to America alongside her husband, choosing to stay put in London and continue her role in foreign service.
That means that Kate is forced to juggle two jobs: ambassador and second lady, which entails flying back and forth from London to Washington, D.C., and fronting like she’s Hal’s happy and supportive wife — instead of his estranged partner.
When we meet Grace’s husband, Todd (Bradley Whitford), he’s bored and feeling useless in his role as second gentleman. He channels his frustration into swimming endless laps in the couple’s sprawling pool, while becoming increasingly concerned about Hal and Grace’s close relationship.
Todd is both fearful that the pair share a romantic connection — they don’t — and that they’re developing a dangerous professional relationship — which they potentially are. “We see it in Todd, how devastating it is to witness that spark in your loved one’s eyes when they’re literally changing the world with someone else,” Cahn says. “It’s intoxicating.”
In Season 2, Kate learns that Prime Minister Trowbridge’s (Rory Kinnear) former adviser Margaret “Meg” Roylin (Celia Imrie) worked with Grace Penn to stage an attack on a British warship. It was supposed to be a strategic move that would help squash Scottish independence and keep a US nuclear submarine base safe. Instead, their master plan accidentally killed 43 people.
When Trowbridge finds out that his ally was responsible for those deaths, he’s furious and out for blood. Roylin is offered asylum in the United States at the start of Season 3, but she turns it down, choosing to die by suicide rather than betray her country further.
Kate discovers that Russia has lost contact with their submarine, which is carrying a highly dangerous nuclear-powered weapon known as the Poseidon, and it’s drifted several miles off the northeast coast of England.
The ambassador convinces Trowbridge that the safest, most effective way to take care of the weapon is to encase it in impenetrable cement, thereby making it impossible for any country to get their hands on it. “No one should have it,” she says. “Not Russia, not China, not you, not us. Bury it — let it rot under the sea.”
Unfortunately, that’s not quite what the Penn administration has in mind.
As the third season concludes, it appears Kate might have finally reached a good place in her marriage. The ambassador has a brief fling with Callum Ellis (Aidan Turner), who works in British intelligence, before realizing that her heart lies with Hal. She pleads with her husband to take her back.
Hal reassures her that he’s “still there,” and the pair reconcile briefly. That is, before Kate realizes that Grace and Hal lied to Trowbridge. They didn’t send an unmanned drone to take photos of the Poseidon — they sent a submarine to capture the deadly weapon for themselves. Not only will that move make Russia furious, but the Penn administration has put America’s entire relationship with the United Kingdom in jeopardy.
“Kate, you will tell no one,” Hal tells his wife. In the last few moments of the finale, Kate watches in horror as her husband and the president ghoulishly pose for photos while the fate of the world order hangs in the balance.
Stream all three seasons of The Diplomat now, and keep coming back to Tudum for the latest Diplomat debriefs. Season 4 premieres on Oct. 15.
