Coltrane back on the case.

ROBBIE Coltrane is back in the world of thrillers, this time with Murderland, and is sat in a trailer in the grounds of a primary school in North London. "For God's sake, they can't find out I'm here," he says. "They'll go wild and they'll be rocking the caravan."

Famous to adults as psychologist Fitz in Cracker, Coltrane's now known to millions as Hagrid from Harry Potter. The thought of the gamekeeper for Hogwarts School of Witchcraft parked next door would surely distract most children.

Murderland is told over three episodes, partly set in 1994 and partly in the present day.

Coltrane plays Detective Inspector Douglas Hain.

"Before you ask, yes, they have to make me look older for the scenes shot in MURDERLANDMonday, 9pm the present day," he says, preening his hair jokingly. "And it's filmed in hi-def," he adds. "It looks amazing, but it's a nightmare for actors like me, you know, who are approaching 40...

"Hain is a time-served cop, not a career cop, and not the sort those around him are about to latch onto. He's not the sort that plays golf with the right people, or is in the Masons or any of that. He's just interested in catching bad people. As we see ITV1, him in the present day, he's winding down for retirement." The first episode sees Sally, played by Lucy Cohu, murdered at home.

Her teenage daughter Carrie (Bel Powley) returns home that night to see the murderer, albeit only a shadow in a dark room. After her mother's death she meets Hain for the first time as he investigates the crime.

During flash-forwards, and in the second and third parts of the drama, we meet Carrie, or Carol as she calls herself as a grown-up, going back to Hain to re-examine the evidence around the murder.

"Carol actually does most of the investigation," says Coltrane, 59. "She's slightly crazed about the whole thing, and it's been eating away at her her whole life. So she goes back to the evidence and finds out more about Hain, and discovers there's something dodgy about him."

CAPTION(S):

Coltrane, 59, as Detective Inspector Douglas Hain