Netflix's political thriller The Diplomat has never been shy about piling on the twists, but Season 3 cranked the tension to a whole new level. With the Wylers climbing the political ladder, a long-buried conspiracy resurfacing, and a finale that left the world teetering on the edge of war, there's a lot to keep straight before Season 4 arrives. If you need a refresher—or you're binging for the first time—here's everything that went down.
From London to the White House: The Wylers' Big Move
Season 3 picks up right after Season 2's jaw-dropper: Grace Penn (Allison Janney) is now President of the United States. Kate (Keri Russell) is immediately thrust into the spotlight, and when the VP slot opens up, she seems like the obvious pick—except Penn offers it to Hal (Rufus Sewell) instead. Hal accepts, but Kate refuses to play Second Lady, opting to stay on as ambassador in London. The two agree to a secret divorce while keeping up appearances publicly, a decision that only complicates their already messy relationship.
Hal's path to the vice presidency isn't smooth. While he's being vetted, he quietly lobbies for the Law of the Sea treaty—something multiple presidents have failed to achieve. Penn is skeptical until Kate tips her off about Hal's ambitious maneuvering. Impressed, Penn gives him the job. But the promotion comes with a cost: Kate's influence in London is now tied to her White House connection, making her job harder and driving a deeper wedge between the couple.
New Romance, Old Feelings
While the American public becomes obsessed with the Wylers' marriage, Kate tries to move on personally. After Dennison (David Gyasi) turns down her advances, she begins a relationship with Callum Ellis (Aidan Turner), a British secret agent. Meanwhile, President Penn's husband, Todd (Bradley Whitford), grows convinced that Penn and Hal are having an affair—denials notwithstanding. Despite the distance, Kate and Hal's lives remain entangled, and their lingering feelings keep bubbling to the surface.
The Conspiracy That Started It All
The fallout from the Season 1 carrier attack is far from over. The world blames Margaret Roylin (Celia Imrie), a former colleague of Prime Minister Trowbridge (Rory Kinnear), but the real culprit is Penn herself. Roylin, under CIA protection, is one of the few who knows the truth. Kate sends Hal to offer her amnesty, but Roylin kills herself instead, putting Eidra's (Ali Ahn) career in jeopardy.
To save Eidra's job, Stuart (Ato Essandoh) suggests she take on the thankless task of evaluating Russian assets. Most of the intel is nonsense, but a former Lenkov colonel claims the U.S. ordered the attack. Kate insists Eidra dig deeper and eventually comes clean about Penn's involvement. Fearing the truth will destroy Penn's presidency, Kate, Hal, and Eidra confront her. Hal urges Penn to tell Trowbridge the truth, but Kate suspects Hal is angling for the presidency himself. In the end, Kate convinces Penn to pin the order on her predecessor, President Rayburn (Michael McKean). Penn reluctantly agrees, but Trowbridge goes rogue and announces Rayburn's involvement to the world, destabilizing U.S.-UK relations.
A Submarine, a Nuclear Torpedo, and a Shocking Betrayal
With Kate's position more precarious than ever, Callum drops a bombshell: a Russian submarine carrying a Poseidon nuclear torpedo is lurking off the UK coast. Trowbridge refuses to speak with Kate, so she calls in Penn and Hal to arrange a summit. When Trowbridge balks, Penn orders underwater drone photos to prove the weapon exists, and Hal pushes Kate to suggest encasing the missile in concrete. Trowbridge agrees, and the crisis seems defused. Amid the chaos, Kate realizes she still loves Hal and asks him to take her back.
But the finale delivers one last gut punch. Callum privately tells Kate that dropping radiation levels suggest the Russians may have recovered the weapon. When Kate relays this to Hal, his reaction reveals the horrifying truth: he and Penn orchestrated the recovery, using the negotiations as cover. The move risks war between Russia and the UK, and Kate is now fully aware of the deception.
What to Expect in Season 4
Season 4 picks up with the world on the brink of war and Kate armed with dangerous knowledge. The stakes have never been higher, and the Wylers' personal and political lives are more tangled than ever. If you're looking for more political intrigue to tide you over, check out our recap of The Lowdown's first season, or dive into seven flawless psychological thrillers that will keep you guessing. And for something completely different, see why Matt Damon's Bourne franchise is dominating Netflix this month.
The Diplomat Season 4 premieres October 15 on Netflix.
