Shaun Evans plays the young Inspector Morse in the "Masterpiece: Mystery" episode "Endeavour." (MCT)

Both Inspector Morse and the man who played him, John Thaw, being dead, and all the books Colin Dexter wrote about the Oxford, England, police detective having long since been adapted, there are only so many ways to go with the franchise.

There is "Inspector Lewis," ongoing since 2006, which focuses on Morse's put-upon sidekick sergeant (regular guy Kevin Whately), who now fills his late governor's shoes, with a Morse-ish assistant of his own (Laurence Fox, intellectual, arty). Four new episodes of that series appear beginning July 8 on PBS' "Masterpiece: Mystery."

You could remake the original novels with another actor, which is pointless, if not just plain wrong: Even though the character was created originally for the page, Thaw is now as inextricable from Morse as wetness is from water.

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A third option, and it is a popular one, is a prequel, the retrospective origin story. "Endeavour," which gets its American premiere Sunday (also on "Mystery") and takes its title from the chief inspector's long-unrevealed first name, takes us back to 1965 and the moment that young Morse (Shaun Evans) returns fretfully to Oxford. Having already left school there, joined the army (with a similar lack of success) and become a policeman, he is now one of a busload of junior officers being brought in from a neighboring jurisdiction to help search for a missing teenage girl.

He is not yet the irascible white-haired terrier we know from "Morse," and Evans, who has something of Thaw's chin and height, does not attempt an obvious imitation of his coming self. But even before we see Morse's newly young face, we are teased with his totems — with the sounds of opera and a glimpse of a crossword puzzle. (Not for the first time — or the last, depending on how you look at it — will a crossword figure into a Morse mystery.) Two fingers type what looks like a resignation letter; living in his future, we know better.

Before "Endeavour" is over, we will have seen Morse introduced to driving a Jaguar (with a cameo appearance by the very Jag he will later own); to his first taste of ale, which he will keep on tasting until the end; and to pathologist Max de Bryn (here played by James Bradshaw). Abigail Thaw, John Thaw's daughter, has a small part as a newspaper editor, possibly just so she can ask Morse if she's met him someplace. And author Dexter, whose stamp of approval, or at least allowance, is on the current series, makes a background appearance, as has long been his practice.

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Worked up by Russell Lewis, who also developed "Lewis" and wrote the "Inspector Morse" episode "The Way Through the Woods," it is a suitably complicated and pictorially engaging work of period suburban mystery, with a large cast of characters (college students, high school girls, snooty academics, a jaded aristocrat, a used car salesman, a beautiful soprano), most of whom I accused at some point of being a murderer, right to their televised face. All but one were not.

Alongside Morse himself, the most vivid character here is a new one, Roger Allam's bearish and paternal Detective Inspector Fred Thursday, a well-centered man with a deep velvet voice who knows talent when he sees it, and gives Morse — who is not ambitious for advancement, but helpless not to work out a puzzle — room to move. (I would watch an "Inspector Thursday" series eagerly.) Meanwhile, four new episodes of "Endeavour" have been commissioned, and that news is better than good.

'Masterpiece: Mystery'

Where: KOCE

When: 9 p.m. Sunday

Rating: TV-PG (may be unsuitable for young children)