Why did The Diplomat kill Dennison? David Gyasi's exit was kept secret right up until the episode aired

All eight episodes of the fourth season arrived on October 15. For three seasons, Dennison had been the one figure in the British government that Kate Wyler, Keri Russell's American ambassador, could actually trust. In season 2, he came within a no-confidence letter of replacing Prime Minister Nicol Trowbridge, and Kate called him one of the most decent people she had known in politics.

How Dennison dies

He is absent from the start of the season, and the show gives a plain reason: Trowbridge, played by Rory Kinnear, has sent him to Amritsar, in India, on government business. At the end of the third episode, Trowbridge tells Kate, her husband Hal and Eidra Park that Dennison's helicopter has gone down and that no one aboard survived.

• The crash — happens entirely off-screen. The death exists only as a line of dialogue.
• The delivery — Trowbridge had meant to tell Dennison's wife first. He blurts it out to the Wylers in the middle of an argument instead.
• The widow — Dennison had married his girlfriend, Thema, in the season 3 finale.
• The cause — the show treats it as an accident. Nobody is blamed, and the season never comes back to it as a mystery.

Even for this show, that's an unusually flat way to lose a main character. It's also deliberate.

What the secrecy hid

Nothing in the run-up to season 4 pointed at Dennison. Netflix's official cast list billed Gyasi as returning, his exit was never announced, and the trailers sold the season on Kate, Hal and a stolen Russian submarine. Viewers found out in the same scene and in the same sentence as Kate did.

That matters because the scene is built around her reaction. A death fans had already read about in a casting story would have landed as confirmation, not as news.

Why Cahn killed him

Debora Cahn, who created the show, didn't enjoy the decision. "It was terrible!" she told Collider, and called it a terrible decision to have to make.

Her reason was about realism, not about Dennison. She pointed to the years The Diplomat has spent filming in the UK.

"There were five different prime ministers, and our show had only had one," Cahn said.

By season 4, Kate had learned the job and knew everyone she was dealing with in London. Cahn said that had started to feel unrealistic, so she took the solid ground away. Dennison was the first piece to go, and Trowbridge's own government came down soon after.

Cahn put the point more bluntly to Entertainment Weekly when she explained why Kate ends up starting over with a new British partner.

"And it just felt dishonest to make it that easy on somebody," Cahn said.

Taking away Dennison was the quickest way to make it hard.

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What his death sets off

Dennison's death is the first domino in London, and the rest fall quickly:

• Trowbridge — comes apart after the crash, hallucinates his late adviser Margaret Roylin in the next episode and resigns midseason.
• Bethan Vaughn — Jodie Whittaker's new prime minister arrives with no interest in partnering with the US, and Kate has to rebuild every relationship she had in Downing Street.
• Kate — loses the one British official who treated her as an equal, right before the season's crisis forces her to choose between her government and her conscience.

Keri Russell, speaking to Deadline, called losing him "monumental, but I also think realistic to these worlds." That second half is Cahn's argument almost exactly. In the real UK, governments fell apart without warning. On The Diplomat, it starts with a helicopter nobody ever sees.

For the record: Dennison spent season 2 being talked up as the man who would replace Trowbridge. In the end, Trowbridge outlasted him by a few episodes.

Previously we wrote: Pretty Woman's original ending was two rewrites away from the movie you know