The Diplomat: Kate Confronts A 'Dangerous' Hal-Grace Duo In Season 4 Trailer — Watch

Three's a crowd, it seems, on "The Diplomat" this season — at least when it comes to keeping an explosive international incident under wraps.

Netflix has released the official trailer for the Keri Russell-led political thriller (which you can watch above), and in it, Kate is still reeling from learning that her husband Hal and President Grace Penn secretly conspired to nab a powerful nuclear weapon from a Russian submarine without telling their U.K. allies about it. Kate directly confronts Hal, and she's blunt: "You stole it." She's concerned that Hal and Grace are "dangerous" together: "Who pumps the brakes when it's you two in the room?" 

Grace's husband Todd senses something is off about his wife, too, and he suggests taking a job in London — forcing Kate to pretend she's enthused about the idea. Kate insists that Grace and Hal's power move is "over the line," and she even tells Grace to her face: "Your tolerance for risk to human life seems higher than it was." (Man, the look that Grace shoots back at her is downright chilling.) Kate hatches a plan to stop them, and it carries a lot of risk as well, judging by the fact that Eidra tells her, "Please tell me you're not doing this."   

Keri Russell stars in "The Diplomat" as Kate Wyler, with Rufus Sewell as her husband (and newly named VP) Hal and Allison Janney as President Grace Penn. Plus, Janney's co-star from "The West Wing," Bradley Whitford, co-stars as Penn's husband Todd. The supporting cast includes Ato Essandoh, Ali Ahn, Nana Mensah, and Rory Kinnear. (Debora Cahn returns as showrunner.)

In Season 4 — debuting Thursday, October 15 on Netflix, with all eight episodes dropping at once — "two marriages threaten to eat each other alive," per the official synopsis. "One catastrophic moment shatters the fragile peace Kate Wyler brokered between the U.S. and U.K., as well as the crumbling marriage she's trying to save. While she fights to stem the bleeding, President Grace Penn and VP Hal Wyler's conspiracy to steal Russia's most powerful weapon hurtles the United States toward war. Kate and Todd, at best an uneasy pair, unite to stop the Grace-Hal alliance from upending the balance of power abroad and at home."

Press PLAY at the top for a sneak peek at Season 4, and then hit the comments below to tell us what you're hoping to see this season.