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Bradley Walsh is not being the cheeky chappie we're used to. But he has something serious on his mind - tonight's Sunday Theatre kidnap drama Torn.

"Filming was very intense," he says gravely. "A couple of days I went home with bad headaches. There were a lot of tears, because, well, you know, it's a dreadful, dreadful situation."

The two-part story begins with a family day out at the beach. Mum Sarah (Holly Aird) is busy with baby Sean. Dad David (Adam Kotz) takes the middle child, Jasmine, to get icecream. That's when it happens - the oldest child, 4-year-old Alice, disappears.

Fast-forward 12 years and the Hoopers are still reeling from Alice's mysterious disappearance. But although mum Sarah passionately believes her daughter is still alive, David has accepted that Alice probably drowned.

But Alice (Jo Woodcock) is very much alive. She is now a rebellious 16-year-old called Lori and believes her parents are Steven, played by Walsh, and his wife Joanna (Nicola Walker, Spooks).

Sarah sees Alice/Lori and knows instantly that it's her daughter. The police are called and when Joanna is asked to produce Lori's birth certificate, she can't. In an act of desperation, she snatched Alice from the beach all those years ago and has brought her up. The drama is based on a true case from America. "Why would you ever think that the person you love had snatched a child in the past?" says Walsh, 47, a father of two. "Steven has been duped. But the important thing to remember is that this drama is about two families with so much love to give."

Nicola Walker's performance as Joanna is heart-wrenchingly sympathetic but the drama doesn't make the characters either angelic goodies or evil baddies. "There are no winners," says Walsh. As Steven's life crumbled, Walsh needed to portray huge depths of emotion. Walsh, who is best known for his role as factory boss Danny Baldwin in Coronation Street, first found fame in Britain as a comedian and host of the game shows Wheel of Fortune and Win, Lose or Draw.

"For actors coming out of long-running soaps it's really important to have a little break from the screen and look for roles that are removed from the ones they have played," he says. "I want to try to help shift perceptions people may have of me as an actor. Does that mean it's only serious roles and no more comedy or soaps? "Of course I would do another soap," he says. "Danny was a super character. I was meant to go back but I've done so many other things, I never found the time." Torn begins on TV One tonight at 8.30pm.