Who died in The Diplomat helicopter crash? The showrunner admits the death 'still hurts'

The fourth season of Debora Cahn's political thriller arrived on Netflix on October 15, all eight episodes at once. Keri Russell stars as Kate Wyler, the American ambassador to the United Kingdom, whose husband Hal, played by Rufus Sewell, is now vice president. Kate's work in London has always depended on a few people inside the British government, and the season takes the most important one away.

Who died

Foreign Secretary Austin Dennison, played by David Gyasi, who has been on the show since its first season. Prime Minister Nicol Trowbridge, played by Rory Kinnear, sends him to Amritsar, India, to meet the Indian foreign minister. His helicopter crashes on the way, offscreen.

Here's everything the season tells you about the crash, and everything it leaves out:

• Where — on the trip to Amritsar, for a meeting Trowbridge sent him to.
• What we see — nothing. The crash is never shown.
• Why it happened — the show never gives a cause.
• Who else was aboard — no other passengers are named.

The news reaches London at the end of episode 3, in a meeting between Trowbridge, Kate, Hal and MI6 chief Tom Libby. Someone hands Trowbridge a note that reads "She's here." Dennison's wife has arrived, and Trowbridge wanted to tell her himself before the news spread. Kate and Hal push to share it, and he doesn't get that chance.

What he leaves Kate with

His last words to her are advice, and they sound different once you know what follows.

"Be patient with yourself. And with Hal," Dennison tells Kate.

Kate isn't patient with anyone for the rest of the season. Losing Dennison sets off a chain reaction in London:

• The funeral — Trowbridge bars the Americans from Dennison's burial.
• The resignation — Trowbridge steps down midseason, after the loss and after Kate blackmails him over a video.
• The new prime minister — Jodie Whittaker's Bethan Vaughn takes over, a leader with Kate's values who still sees the Americans as the problem.
• The secret — Vaughn discovers that the U.S. took the Russian Poseidon torpedo, and agrees to let Russia retrieve its submarine crew in a way that would expose the theft.

Each step follows from the one before it. Without Dennison in the room, nobody in the British government is left to slow things down for Kate.

Dennison was the British official Kate could always reach. Within half a season of his death, the government she knew is gone.

By the finale, at the G7 summit in Tuscany, Kate has resigned as ambassador.

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Why Cahn killed him

Not because the character had run out of story. By season 4, Kate had a foreign secretary who trusted her and a prime minister she knew how to handle, and the show decided she couldn't keep both. Cahn told TV Insider that the decision "was not a happy revelation."

"It just felt dishonest to make it that easy on somebody," Cahn told Entertainment Weekly.

Cahn also admitted to Entertainment Weekly that losing him "still hurts."

Previously we wrote: Austin Dennison's fate in The Diplomat season 4: the showrunner explains why it had to be him