One of Us (BBC1, 9pm)

WELL, well. Another gritty British drama where the protagonists hate each other about as much as we dislike them ourselves. Around 40,000 litres of fake rain were required up in the Scottish Highlands as neighbouring families, the English Elliots and the far from welcoming Douglas clan find a nightmare on their doorstep in this four-part drama from writers Harry and Jack Williams – they previously wrote The Missing.

Childhood sweethearts Adam Elliot and Grace Douglas are brutally murdered shortly after returning home to the village of Braeston following their honeymoon. Then the alleged killer crashes his car into the families neighbouring homes during a raging storm. He needs help, but the thirst for revenge soon gets in the way.

Pitched as more of a whydunnit than a whodunnit, the main benefit to viewers is that the cast includes Juliet Stevenson, Joanna Vanderham, Julie Graham, Joe Dempsie, John Lynch and Gary Lewis, who will be forever recognised as Billy Elliot's father in the North-East-set film.

Stevenson tells TV Times: "It lifts the lid on all sorts of secrets about what's gone on in the past between the two families, but as you watch them spiral out of control, you don't want to judge them too quickly because they go through is so extreme."

Lewis adds: "It's like watching Titanic. You can't help asking yourself, 'What would I do in that situation?' I play Alistair, who's worked on the Douglas farm for decades and he;s also faced with this difficult predicament. He's complicit in an evolving decision about what to do and the desire for revenge is so powerful."

While considering their next move, skeletons are unearthed and old wounds reopened. It becomes clear that everyone involved has something to hide, and that living with the consequences of their actions is going to be very difficult indeed.

"The drama asks the viewer, 'what would you do?'" says Jack Williams. "What if the person who did the most terrible thing to you, turned up on your doorstep?"

Stevenson adds: "One of the challenges of this role was to have to imagine what it's like to have a child murdered. I have four kids and it's something I don't want to think about. I Googled 'parents of murdered children' and up came forums where parents have had that experience and I read endless heartbreaking accounts."

Vanderham appears to the only voice of reason as the plot unfolds. "Claire works as a care home nurse and is constantly shocked and stunned by how the people closest to her react. She seems to be the only one saying that they should leave it to the police. But because they end up disagreeing so fundamentally it's the beginning of a fracture within her close-knit family and Claire constantly questions her own moral compass."

Inside the Factory: Sweets (BBC2, 8pm)

GREGG Wallace helps to unload a tanker full of sugar from Norfolk and follows it through one of the oldest sweet factories in Britain – Swizzels in Derbyshire – to see how more than 500 workers, as well as some mind-boggling machines, transform it into more than 100 million individual sweets within 24 hours. Cherry Healey finds out how the letters are put in seaside rock and is given special access to the Fisherman's Friend factory in Lancashire to discover how a local family turned a niche product into a worldwide success.

Rookies (ITV, 9pm)

THIS time the documentary follows trainee officers in Surrey Police, charting their progress as they venture out onto the streets under the watchful eyes of experienced veterans. Rookie law enforcers include 29-year-old Tyne, who has made a radical career move from dance instructor to trainee Police Officer. Cameras also follow 19-year-old Angus, who is leaving a close family home in rural Somerset where he worked in a call centre, to take on a career which will push him to his limits.

Viv Hardwick