The stars of new BBC One legal thriller The Victim believe viewers will be hooked from the start.

The drama focuses on how the law is dealing with social media being used to "out" suspected criminals.

Kelly Macdonald stars as the mother of a murdered child who is accused of illegally identifying a suspected killer online.

The Trainspotting and Boardwalk Empire star is joined in the line-up by former Rebus actor John Hannah.

The four-part show airs on consecutive nights from Monday to Thursday and the stars hope it will spark a debate about how people get their news.

John Hannah told BBC Scotland's The Nine programme: "I think people will get hooked on the show right from the get-go, and they will find themselves instinctively making choices about the characters. Who's right, who's wrong - and then switching."

Kelly Macdonald plays Anna Dean, whose nine-year old son was murdered 15 years ago. She is accused of revealing her son's killer's new identity online and conspiring to have him murdered.

She said: "Anna is a mother, a family woman, who has had a very tragic thing happen to her years before. She may or may not be guilty of a crime."

Mother-of-two Kelly said making the show was an emotional challenge - but filming in her native Glasgow helped.

She said: "It was brilliant. I got to sleep in my own bed every night."

In the show, hard-working family man Craig Myers, played by James Harkness, is the victim of a vicious attack after he is accused if being the boy's killer.

John Hannah plays DI Grover, an experienced detective investigating the attack on Myers and trying to discover who made the online accusation against him.

Monday night's first episode was set on day one of a criminal trial at the High Court in Edinburgh.

The Victim follows the legal proceedings, while also covering the events leading up to the trial.

John Hannah said: "It starts in court and you see what's happening pretty much right away. And then there's the parallel story of the past and how things have unfolded to get to where they are.

"Everyone will have a very emotional connection to the show as they watch it.

"People will make decisions and then over the four episodes they'll question how they have done that.

"If that sort of thing happens in a broader sense with the news and the media, then that's good."

The show's creator Rob Williams says Craig and Anna are pitted against each other, but viewers' sympathies will be divided.

New potential suspects will be revealed and long-buried secrets are unearthed as the story builds to find out who really is The Victim.

Writer Williams says The Victim is not based on a true story, and is not inspired by any one case in particular.

Asked about "parallels" with the 1993 murder of two-year-old James Bulger and subsequent attempts to expose the new identities of his 10-year-old killers Robert Thompson and Jon Venables, Williams said: "Well it's not based on any one case, on any existing case.

"It explores a territory that, sadly, there are many cases in which juveniles have committed horrific offences, and not been named for legal reasons. Some of whom have been given new identities.

"So it's a territory we explore - it's not about any single case. It's hopefully a very even-handed treatment of a very emotive issue, and it is entirely fictional."

The Victim is on BBC One at 21:00 from Monday to Thursday this week.