Season 4 of The Diplomat lands on Netflix on October 15, 2026. The full trailer reveals a fresh political crisis in which Kate Wyler must take on an alliance between President Grace Penn and her own husband, Hal.
In the wake of Season 3, Kate learns that Grace Penn and Hal Wyler took part in a covert operation to seize Russia's most formidable weapon. The clandestine move now threatens to drive a wedge between the United States and the United Kingdom, and could even propel Washington into a new war.
Kate is working to safeguard the diplomatic balance she helped establish between the two nations. She finds an unlikely ally in Todd Penn, the president’s husband, who shares her worries about the thaw between Grace and Hal and the consequences of their decisions.
The season centers on four characters whose public duties and private lives intertwine: Kate and Hal Wyler, Grace and Todd Penn. The political maneuverings of some strain the others’ marriages, while decisions from the White House directly jeopardize the Anglo-American alliance.
Keri Russell reprises the role of Kate Wyler opposite Rufus Sewell, Allison Janney and Bradley Whitford. Nana Mensah, who plays Chief of Staff Billie Appiah, also joins the regular cast, alongside Ato Essandoh and Ali Ahn.
Allison Janney clinched the September 2026 Emmy for Best Supporting Actress in a Drama Series for her portrayal of Grace Penn. The award covers episodes that have already aired, but it comes as her character has become one of the driving forces of season 4.
Created by Debora Cahn, The Diplomat blends political thriller with a global crisis and a marital drama. The first three seasons are already available on Netflix.
To catch the rest of this month's new releases, check out our guide to October Netflix titles, our roundup of new streaming releases across all platforms, and today's streaming picks: “What to watch today in streaming.”
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