Is The Undoing properly great or just a run-of-mill thriller with a brilliant casting director?

There must be some people somewhere who vaguely know their own spouses — but if so, they don’t tend to appear in domestic-based thrillers. Last week when Sky Atlantic’s The Undoing began, Jonathan and Grace Fraser (Hugh Grant and Nicole Kidman) seemed to have the happiest of middle-aged marriages. They still laughed at each other’s jokes. They still kept each other fully informed about the kind of day they’d had at work: he as a kindly child oncologist, she as an unfailingly wise therapist. Not only did they still have sex, but when they did, it wasn’t always in bed.

True, they weren’t wholly without their problems. Their loving son Henry, for example, sometimes didn’t clean up after making smoothies. Nonetheless, even their equally rich and pampered peers on New York’s Upper East Side regarded Jonathan and Grace with obvious envy.

Two episodes on, and their gilded life has duly been obliging enough to fall apart.