A Very British Scandal (Prime Video)

Following her divorce, Margaret Sweeny (Claire Foy), the only child of a Scottish millionaire, meets Ian Campbell (Paul Bettany), who's destined to be the next Duke of Argyll, on a train. He invites her to visit his castle, and although it's a bit run-down, Margaret sees potential. Especially when Ian shows her a sunken ship just off his land that's reported to have a fortune stowed away on it.

Although Ian is married with two sons, Margaret begins an affair with him, and as soon as Ian is divorced, they marry. However, he soon shows a side of himself that she hadn't seen before, while Margaret turns out to be far more devious than he could have expected.