Hugh Grant wonders why he can’t cuddle with the dog in “A Very English Scandal.” (BBC)

The theme music for “A Very English Scandal” is played by a bunch of buoyant violins, shimmering and flirting as if to say, “You won’t believe what you are about to see.”

And indeed, the three-part BBC miniseries now streaming on Amazon is pretty unbelievable. At a time when homosexuality was illegal in Britain, a powerful member of Parliament writes love letters to a stable boy, calling him “Bunny.” In ink! On paper! A man shoots a dog on a dank and foggy night. In a murder trial, the judge tells the jury that the intended defendant was “an accomplished sponge.”

But this tale is in fact based on true events. Member of Parliament Jeremy Thorpe befriended young Norman Scott back in 1961. He wrote him many loving letters. And he was accused of ordering a hit on his former lover to stop him from speaking out.

It was, as the title says, a very English scandal: Buttoned-up people did stupid and horrible things while keeping up civilized public personas.

Hugh Grant portrays Thorpe, dandily dressed in fine suits with vests and a derby hat. His chipper grin grows increasingly frownish as Scott keeps stirring things up, mainly because Scott wants Thorpe to get him a National Insurance card. In a brilliant stroke, Patricia Hodge, playing Thorpe’s sour mum, has exactly the same grimace on her face as she says unmotherly things to her son like, “Of course you’re ruined. You know that, don’t you?”

Lanky Ben Whishaw is spritely, dog-loving Scott, with poofy hair and a lot of charm but also a lot of courage, declaring in Thorpe’s trial: “I will talk. I will be heard. I will be seen. One thing you will not do is shut me up.”

The series is a brilliantly hilarious exploration of the lies people tell and what they think they can get away with — including murder. It is about the secrets politicians keep and the people they trample over. With three hourlong episodes, it is the perfect length for a summer mini-binge.