Secrets and lies exposed in J K Rowling’s adult drama The Casual Vacancy

JK Rowling's bestseller The Casual Vacancy comes to our TV screens - the tale of a phantom blogger who threatens to expose the dark secrets of the inhabitants of a rural English town.

The Casual Vacancy cast, front row, from left, Sir Michael Gambon, Rufus Jones, Shirley Mollison, Julian Wadham and Emilia Fox. Courtesy Steffan Hill / BBC / Bronte Film and Television Ltd

We all have a few skeletons rattling around our cupboards – but it is big and scary news for the residents of a sleepy English town when a phantom blogger threatens to air all of their dark, dirty secrets online.

This is the dramatically delectable premise of The Casual Vacancy, a BBC mini-series based on Harry Potter author J K Rowling's first novel for adults, which became a worldwide bestseller in 2012. It dissects the secrets that lurk and conflicts that fester behind closed doors in a seemingly idyllic British town, where the burbling of the brook doesn't sound all that different from the gurgling in a dying man's throat.

When the vacancy of the title opens up on the parish council of Pagford – due to the sudden death of beloved social crusader-councillor, Barry Fairbrother – it pits the local privileged “haves” against the less fortunate “have-nots’.

A political civil war erupts and the townsfolk who call the cobbled streets and ancient abbey home will never be the same.

For any novelist, the goal is to create tension on every page, and this three-part mini-series, which debuts tonight on OSN First HD, translates that golden storytelling rule to every scene.

In this town of curtain twitchers – where everybody is suspiciously watching everyone else – rich and poor, parents and children, wives and husbands, teachers and pupils, go to war.

At the heart of the battle is the future of Sweetlove House, a community centre that provides treatment for drug addicts and a food bank for the poor, among other services, but which could soon be turned into a luxury spa and tourist attraction by the greed of developers who hope to drive the junkies and underprivileged as far from the town as possible.

Fairbrother held the swing vote that could have blocked the spa and preserved the town's vital social safety net. He is played with conviction and an earnest charisma by Rory Kinnear, who will be familiar to fans of recent James Bond films and TV's Ashes to Ashes and Penny Dreadful.

Now Fairbrother is gone, and with him his sense of social justice and responsibility, but has some part of him survived?

His “ghost” – a mystery blogger using his name – soon provokes outrage and controversy in the ensuing power vacuum and the political contest for the future, and soul, of Pagford. A superb ensemble cast illuminates the many sorry recesses of human folly, including one absolute standout – Abigail Lawrie, in her first TV role as troubled 16-year-old Krystal Weedon.

To the town, she's all trashy swagger, sass and potty mouth. At home, she's brave and selfless as she cares for her heroin-addict mum (Keeley Forsyth from Waterloo Road) and four-year-old brother.

“There will definitely be people who recognise my character,” says Lawrie. “I think the story is about helping each other, about collective responsibility and living in a community.

“Treating others how you would want to be treated – that’s the message. There are millions of Krystals out there.” The villain of the story is Howard Mollinson, a smug, self-satisfied delicatessen owner who, as chairman of the parish council, sees himself as The King of Pagford. He views Sweetlove House as an eyesore.

Craftily portrayed by Sir Michael Gambon – one of Britain's most celebrated actors. from early work such as Dennis Potter's The Singing Detective (1986), to more recent films such as Quartet (2012) and as Dumbledore in the Harry Potter movies – Mollinson is all twinkle and bonhomie, but with a heart of coal.

The Casual Vacancy boasts too many stars and characters to list here – but all are praiseworthy in that not one of them hits a false note in their varied roles.

“It’s a big cast – and the young cast, especially, are brilliant,” says Gambon.

• The Casual Vacancy airs at midnight on Monday on OSN First HD