For veteran British actor Martin Shaw, portraying Adam Dalgliesh, the detective at the heart of "Death in Holy Orders," presented a particular challenge.

"He doesn't say a whole lot," said Shaw. "It's one thing in a book -- you can describe what goes through the character's mind. But you can't do that on the screen."

Shaw stars in PBS's "Mystery!" adaptation of P.D. James's 2001 crime novel. Part one aired last week, introducing Scotland Yard detective Adam Dalgliesh as he begins an investigation of a death at a theological college.

Shaw's solution in playing the role was to "be very certain of his thought processes and make it look like I was always about to say something but couldn't quite get it out."

Shaw had not read any of James's novels before taking the part."Then I met her [on the set] and spent half a day with her," he said. "She is really like the American idea of an English dame, a very grand old lady and she has a brain like a laser."

James was pleased by Shaw's portrayal. "It's a difficult part, a very cerebral part, and I know actors like to have a lot of action," she said. "But what happens to Dalgliesh happens in his brain, as he brings order out of disorder, justice out of injustice. And we have to see it in his face. TV is very good for that. You see the face on that small screen, and Martin does it exceptionally well."

Director Jonny Campbell found the book's adaptation challenging on several fronts. "Initially it was finding the location to represent this college," he said. "It was a piece of [James's] imagination, so it didn't exist. She sets most of her crime novels in Suffolk. So we trolled the whole coastline looking for something that vaguely resembled the college. We created, as she did in her mind, the location from about eight different buildings."

The fictional St. Anselm's, located on a desolate British coastline, is the site of a death that may not have been accidental. Dalgliesh, who spent time at St. Anselm's in his youth, returns to probe the scene.

Questions about the death -- that of a seminary student found smothered by sand -- are soon expanded to include other incidents. The quiet facade of Dalgliesh, a poet as well as a crime solver, is the center of the swirl of events.

Campbell was concerned about losing some of the drama's suspects. "We did away with a few characters for logistical reasons and there are still about 15 potential suspects," he said. "And one of the difficulties is introducing them all as our suspects, hopefully so they'll stay in people's minds."

Robert Jones adapted the book for the program, and agreed with Shaw's description of Dalgliesh.

"He tends to cogitate and work things out, but you can't watch that too long," he said. "I did mention to P.D. James that Dalgliesh doesn't say anything, and she just smiled, as if to say that was my problem. She did have a suggestion or two, but she was very hands-off."

James spent a day on the set but did not review Jones's script. "If I saw the script, I'd want to rewrite it," she said.

But for a scene in which Dalgliesh interviews a woman, she pointed out that the very proper Dalgliesh "would not say 'I'd like to see Agatha.' He would not use the first name of a lady he had not met," she said.

Shaw said that the rugged locations of "Holy Orders," made conditions difficult at times. "It was filmed during the winter, and it was beautiful but the weather makes for difficult filming," he said.

When Dalgliesh plunges into the sea in a rescue attempt, "I had a wet suit on under my shirt," said Shaw. "And I was torn between the vanity of not looking two stone, or 28 pounds, heavier, or freezing my nuts off." he said.

"And the decision was made that it was far safer from an insurance point to just wear the wet suit."

Death in Holy Orders

Sunday at 9 p.m. on PBS