River (BBC1, 9pm)

STELLAN Skarsgard says he was drawn to this dark and complex cop series, where he plays John River, a brilliant police officer whose genius and fault-line is the fragility of his mind.

"If it was a normal TV series, it would be rather easy to tell you about it, but it's not – and that's why I'm in it," says Skarsgard, The big attraction for him was a scirpt by award-winning British playwright and screenwriter Abi Morgan (who wrote The Hour and 2011 film The Iron Lady).

"This is my first real TV series and I did it because of Abi's script. She's a special writer, very poetic and not at all linear in her storytelling. It's a crime story on the surface, but it's really more about a person's breakdown or his psychological status. It's a mixture of the danger of illegal actions and psychological vulnerability."

The actor's police officer is haunted by dead and dying victims and killers from unsolved murder cases. The figures that drift in and out of his consciousness are "manifests" – figments of his imagination that enable him to discover the truth behind the crimes he investigates.

"We're not talking about ghosts here; he produces these dialogues himself," explains the 64-year-old, whose credits also include The Girl With The Dragon Tattoo, Mamma Mia!, Thor and this year's Cinderella. "They are an internal discussion – almost a checklist from which to investigate the victims' lives and the moments leading up to their death. It's a tool to the drama."

Tonight's episode sees River battling to come to terms with the recent loss of his dearest friend and colleague, DS Jackie "Stevie" Stevenson, played by Last Tango In Halifax's Nicola Walker. "When you meet River, he's in a car together with his colleague Stevie, but she has been murdered three weeks earlier. Very often the victims of murder cases show up and have discussions with him, and try to help him solve the crime," Skarsgard says.

Thomas Cream (played by Eddie Marsan), is a notorious killer who plagues the crime-fighter.

"He's representing the very darkest side of River; the self-destructive and suicidal side that, when it manifests, is threatening to pull him down. It's an on-going fight with his demons," notes Skarsgard.

The straight-talking protagonist believes River to be "self-aware", as opposed to delusional.

The series was shot in East London, but Skarsgard insists he hasn't picked up any Cockney rhyming slang. "It's fun and an incredible culture, but it's hard to understand," says the father of eight (six with his first wife, My, and the youngest two with second (and current) wife, Megan Everett).

One of his brood is True Blood actor Alexander Skarsgard, who is taking the starring role in David Yates' adaptation of Tarzan, due for release next year.

"He was shooting Tarzan at the same time we were doing River," says Skarsgard senior. "He was on such a strict diet that he would only have small portions every three hours, and then two in the days before he wrapped filming. He actually moved in with us, because he knew he would get food."

The Yorkshire Vet (C5, 8pm)

Julian Norton is dispatched to a local petting farm to attend to a goat with a suspected broken leg, but he quickly realises his patient has a bad temper, and is adverse to treatment. Meanwhile, things seem grave when Peter Wright receives an emergency call from the anxious trainer of a horse that has cut open its hoof while grazing in a field.Later, Julian and Peter take an afternoon off to attend the Great Yorkshire Show, where they bump into clients old and new.

Lewis (ITV, 9pm)

THE murder of the young avant-garde artist Talika Desai is linked to the unidentified human remains discovered in the well, and the subsequent investigation takes Lewis, Hathaway and the team deep into the world of drugs, social media, alternative art and the growing Eastern European homeless community. Crime drama, starring Kevin Whately, Laurence Fox and Steve Toussaint.