The Diplomat Season 3 premiered on October 16, 2025, with all 8 episodes released simultaneously on Netflix.
Season 3 made both the political and personal lives of the characters as complicated as possible. First, President William Rayburn unexpectedly passes away, and Vice President Grace Penn is now running the free world. Instead of choosing Ambassador Kate Wyler for VP, she offers the role to Hal Wyler, Kate’s husband. Hal accepts.
Kate, meanwhile, is left holding the diplomatic bag in London, managing international crises while her career gets outmaneuvered in D.C. She is stuck being ambassador when she could have been writing her own legacy, but now she is just the Second Lady.
Meanwhile, Hal is thrown into the shark tank of American politics, juggling loyalty to his wife while running the country alongside a president who is not known for being transparent.
There is constant tension: is Hal playing his own game, or is he just getting played? There are also whispers about him and President Penn sneaking around with secret agendas.
There is also a subplot where Hal and President Penn are possibly covering up a conspiracy involving a Poseidon nuke. Kate, stuck in the middle, has to figure out who is lying, who is scheming, and whether she can trust anyone at all.
The intricate and convoluted situation of loyalty, ambition, and deceit makes the audience doubt who is the actual master of the finely spun web of international diplomatic power.
Who has the real political stronghold in The Diplomat Season 3?

In The Diplomat Season 3, President William Rayburn's sudden and unexpected death triggers a significant adjustment of U.S. political influence. Without Rayburn, Vice President Grace Penn becomes president, but Penn's ascension is in no way unchallenged.
From the outset, it is evident that Penn's presidency is controversial both at home and abroad. Her governance is characterized by strategic political movement, risk-taking on a carefully calibrated scale, as well as moral grayness.
In the early stages of her presidency, Penn solidifies her power with a decisive and controversial choice: she appoints Hal Wyler, husband of U.S. Ambassador Kate Wyler, as vice president.
By passing over Kate herself, who was a powerful player and probable future candidate for greater office, Penn not only solidifies her own political foundation but eliminates potential insurrection within the executive office.
The choice illustrates Penn's awareness of the relationship between interpersonal ties and political power, literally tying a significant player, Hal, to her own administration while guaranteeing loyalty from powerful individuals.
The political plot thickens in The Diplomat Season 3 with the false-flag British aircraft carrier HMS Courageous attack staged by Penn in tandem with British political advisor Margaret Roylin. The purpose of the attack was ostensibly not to inflict direct damage, but as a unification event for Britain. Penn's strategic aim was to thwart the Scottish independence referendum, as its successful passage would put at risk U.S. access to an important Scottish navy base used to track Russian military operations.
Though the mission was intended to be symbolic, it unfortunately got out of control and ended in a tragic loss of 43 British sailors' lives. First, Penn tries to deflect blame onto the deceased President Rayburn to save herself, but facts are revealed in due course, leading to domestic as well as international political upheaval.
The revelation of Penn's participation in the HMS Courageous attack causes a rift between the US and the UK. The British Prime Minister, Nicol Trowbridge, publicly reveals the truth, exposing the risky crossroads of personal aspiration and state affairs.
Despite the fallout, Penn justifies her actions in conversations with Ambassador Kate Wyler, emphasizing the strategic necessity of the operation. She explains that the unifying calamity was intended to prevent Scotland from voting for independence, which would safeguard U.S. interests, and admits that while the attack was supposed to avoid fatalities, the situation escalated beyond her control.
Further complicating the political scene is the revelation of the Russian nuclear-capable submerged drone Poseidon off the British coast. Penn and Hal Wyler arrange its retrieval without British government clearance, highlighting Penn's readiness to act unilaterally and the power that Hal enjoys within the administration.
The clandestine retrieval escalates the stakes globally while emphasizing the blurred lines between lawful authority, personal ambition, and strategic calculation within Penn's leadership.
On the other hand, Kate Wyler, who was not chosen for the vice presidency, continues her position as U.S. Ambassador to the United Kingdom and exercises her power through diplomacy. She opts to stay in London instead of pursuing a higher-positioned political role, demonstrating a sophisticated view of power: influence can be mightier when not directly wielded, and personal virtue can be a form of political strength.
Kate's role illustrates the difference between Penn's explicit power consolidation and the quiet, clever methods of other players, who are noticeably less aggressive in their tactics. By the end of Season 3, it is evident that political power is not just the president's official title but also lies within the Grace Penn–Hal Wyler partnership.
Both individually are a powerful mix of authority, strategic maneuvering, and control over critical people and institutions. Although Penn possesses the official prerogatives of the presidency, the series makes it clear that power frequently lies within the complex interweb of relationships, loyalties, and rationalized risks, a terrain where desire, diplomacy, and personal ties are as significant as office itself.