‘The Diplomat’ Creator on Kate and Hal’s Marriage and Season 3’s Horrifying Last-Minute Twist: ‘There’s Nothing a Character in This Show Does That We Can’t Justify’

Spoiler Alert: This story contains spoilers from Season 3 of “The Diplomat,” now streaming on Netflix.

We’ve met before, “The Diplomat” creator and showrunner Debora Cahn and I, with Keri Russell, in New York, before the second season of the farcical political thriller dropped. Back then, at an Upper Westside bistro, Cahn, Russell and I had lots of drinks — the kind that, Cahn says, leave you “foggy the next day, and yet you do it anyway.” “I started doing it at 17,” she says, “and here I am at 50-something still doing it.”

We don’t learn.

And that’s partly…