Success of ‘Mystery!’ Is No Puzzle to Fans : Television: British whodunits in PBS series are strong in plot and dialogue. The season finale begins tonight, but there will be summer repeats.

Some people kill for cocaine. Some people scour the world for the perfect chocolate. You can bet that some people reschedule their lives around Tuesday nights so they can see what that zany Roseanne is up to this time!

We prefer British murders and mayhems as encapsulated in PBS’ “Mystery!” Ours is a hard addiction. To displace us on Thursday nights (8 o’clock on Channel 50, 9 on Channels 28 and 15), would take the Lakers winning the playoffs (we’re safe this year) or a serious world war.

We refer to the tales of intrigue with our old friends, the prissy Jane Marple, the boorish Sherlock Holmes, the remote but wily Commander Dalgliesh.

Most of these imports are thick in character, from the starring personalities through the casts. They are rich in plot and dialogue, so that often you can make new discoveries on rewatching a program. On frequent occasion, looking at a rerun sometimes years later, we will have forgotten who done it.

“Mystery!” ends its 10th season with a two-parter that begins tonight, “The Last Enemy,” starring the mush-faced old romantic Inspector Morse, as created by Colin Dexter and as played by John Thaw. Morse, this time, is dispatched to Oxford to check out some unpleasantness.

Summer repeats follow June 14, but if you’re new to the English manner of death, the adventures of the crafty barrister Horace Rumpole, Sherlock Holmes and Morse will constitute a hearty menu, along with back-to-back British series of mostly PBS repeats on Arts & Entertainment cable. They play Monday nights, the “Agatha Christie Hour” at 6 and “Masters of Mystery” at 7 (the same installments air again at 10 and 11 p.m. Mondays).

For aficionados, the worry occurs, of course, that the British will run out of mysteries and we’ll end up with reruns of “Quincy” and “Hunter.”

At WGBH in Boston, Rebecca Eaton, who executive produces both “Mystery!” and “Masterpiece Theatre,” chortled at the notion: “We’ll run out when we run out of crime,” she said. “There’s a renewed fascination in the mystery genre over the last five years, I would say, first in British television--and therefore on ‘Mystery!’--and then on the networks in this country and cable.

“There is kind of an endless supply because it’s such a well-established genre that it can take so many forms. And we haven’t yet plumbed the depths of the British mystery writers and potential mystery series. There are several very strong writers from the ‘20s, ‘30s, ‘40s, ‘50s, whose turns will come, I hope.”

The bad news is that we’re out of Miss Marples: “It was (star) Joan Hickson’s choice,” Eaton said. “She is 81 and, you know, she just did one last year.” (This two-part story ran on A&E.;)

The better news is that David Suchet has committed to doing 36 hours of Agatha Christie’s inscrutable Poirot, including a second series for next season.

(Not incidentally, A&E; will run the American premiere of a curious tale June 17, “Murder by the Book,” which pits Dame Agatha herself against Poirot himself, with Dame Peggy Ashcroft as our aging writer and Ian Holm as the waxy Poirot. In it, Poirot tries to argue the writer out of killing him off in in her last book.) Also on the agenda: More stories with Margery Allingham’s Campion (Peter Davison); “De Kinder,” a chiller about a British woman who storms into the terrorist underground to rescue her children, and a suspense miniseries on the creepy novel “Mother Love,” with “Mystery!” host Diana Rigg playing the diabolical London divorcee-killer.

In the works: Peter O’Toole in a Gothic mystery, “The Dark Angel,” based on the famous 1864 book by Sheridan Le Fanu, “Uncle Silas.” There are more Holmeses coming from Jeremy Brett and plans are hot afoot to develop P.D. James’ latest Dalgliesh book, “Devices and Desires.” Eaton also reports projects under way on the works of New Zealand detective novelist Ngaio Marsh and the prolific French author Georges Simenon’s cunning Inspector Maigret.

To realize that there’s so much treachery, conniving and slaughter around is a warming thought to us “Mystery!” loyalists. Thank you, thank you.