The new HBO show War stars Dominic West and Sienna Miller as a rich and famous couple kicking off one killer divorce. Staffing their respective law firms — Cathcarts & Sons and Taylor & Byrne — are a cast of British character actors whom you’ve seen before in shows like The Crown, Andor, and The Great.

But who plays Flora Monroe, the gorgeous girl who ensnares Martin Henderson (Dominic West) in a classic “honeypot” scheme at the behest of his wife, Carla Duval (Sienna Miller)? And where have you seen Rose Williams before?

**Spoilers for War Episode 1 “It’s Done,” now streaming on HBO Max**

HBO’s War opens with tech billionaire Martin Henderson winning an award for his work creating Zephyr, a social media site that’s supposedly a net good for humanity. During his acceptance speech, he catches the eye of a gorgeous twenty-something in the crowd. Later, when he arrives at his hotel — yes, he’s staying at a hotel even though he and his wife own a luxurious apartment in London — this mystery woman is there. They get off on the same floor and then they, uh, get off.

What seems to be an organic one night stand is soon revealed to be somewhat more nefarious. The next morning, Flora snaps a provocative pic of them in bed together and then sends it to Carla, saying over the phone, “It’s done.” Carla then brings this evidence of Martin’s infidelity to her lawyers, Nicholas Taylor (James McArdle) and Serena Byrne (Phoebe Fox), with the directive that they not only file for divorce, but come up with a way to break their pre-nup so she gets half Martin’s Zephyr fortune.

Okay, but who plays Flora in HBO’s War? And where have you seen her before? Here’s everything you need to know about Rose Williams, the actress playing Flora in War...

Who Plays Flora Monroe on the HBO show War? Meet Rose Williams

32-year-old English actress Rose Williams plays Flora Monroe in HBO’s War. She’s the beautiful “honeypot,” literally dressed in honey-tinted gold, who seduces Martin at the start.

Rose Williams has appeared in Mrs. Harris Goes to Paris, The Power, and Reign. However, she might be best known for playing the spirited heroine of Masterpiece on PBS’s Sanditon. That show was inspired by Jane Austen’s final unfinished manuscript, with Williams playing young Charlotte Heywood.

“She’s so talented, Rose, and she’s really constructive and part of the conversation about how to storyline [Flora’s plot],” War creator George Kay told DECIDER. “So it was fun.”

You can follow Rose Williams on Instagram @rosevictoriawilliams.