The only thing in favour of Unchosen is the number of episodes. Imagine if one had to plod through eight episodes instead of six. Conversely, four would have been better than six, and one could go on.

Stories set in secret cults are always fascinating given the ritual, rules, costumes, charismatic leader, taboos, the frisson of crossing the line between desire and duty, and physical and psychological violence.

Amazingly, Julie Gearey has put these elements together to create a show that is as dull as ditchwater. Inspired by a chance meeting Gearey had with a woman belonging to a cult at a grocery store and real-life conservative religious groups including the Plymouth Brethren, Unchosen starts off half-way promising but soon devolves into earnest silliness.

Rosie (Molly Windsor) lives with her husband, Adam (Asa Butterfield), who is a rising star in their religious order, Fellowship of the Divine, and their six-year-old daughter Grace (Olivia Pickering).

Rosie’s sheltered and restricted life falls apart when Grace, who is hard of hearing, wanders off and falls into a lake. She is rescued by a stranger, Sam (Fra Fee), towards whom Rosie feels gratitude and unease.

Though Adam’s brother, Isaac (Aston McAuley) uses a cell phone to get Grace to the hospital quickly, it violates the rules in the Fellowship of the Divine and he has to be punished. The leader, Phillips (Christopher Eccleston) wants Adam to prove his loyalty to the fellowship through his treatment of his brother’s transgressions.

It is not just the phone for Isaac, as he wants to leave his wife Hannah (Alexa Davies) and the cult to be with the woman he loves. Meanwhile, Sam has ingratiated himself with the fellowship to the extent that no one looks too closely at his history.

Every twist and turn can be seen a mile away and if you still do not get it, the subtitles helpfully say “ominous music.” It is a shame to see all these wonderfully talented actors defeated by lackadaisical writing.

Butterfield, who was engaging as Otis in Sex Educationis reduced to telegraphing confusion with a mild frown. Where is the heartbreak and ruination as one’s beliefs, and all that one holds dear, come crashing down?

The same is true of Windsor, who is either running frantically like Tom Cruise or looking tremulous. Fee looks menacing and vulnerable by turns while Eccleston is a textbook repressed elder. Where Jimmy in 28 Years Later: The Bone Templeis all smiles and tenderness with a chilling side of psychopathy, Phillips is patriarchy wielded like a sledgehammer.

Siobhan Finneran (O’Brien from Downton Abbey) as Mrs Phillips is even more poorly served. She is the standard-issue moral authority figure, with no interior life whatsoever.

Unlike other cult shows, including Under the Banner of Heaven, where religion is a lived reality for its characters, Unchosen leans towards gestures and music to signal important things are being felt.

This is funny for a bit and then just gets tiresome. None of the transgressions feel earned because no time is spent on the effect of a character going against a belief system they have grown up with.

While the impossibly hilarious ending signals the possibility of a sequel, one can always hope better sense prevails.

Unchosen is currently streaming on Netflix