The Season 2 finale of “Endeavour” left its title character, Detective Constable Endeavour Morse (Shaun Evans), in dire straits. An investigation into horrifying physical and sexual abuse at a boys’ school reached a climax with Morse being arrested on murder charges, framed by a highly placed police official who also gravely wounded Morse’s senior officer, Detective Inspector Fred Thursday (Roger Allam), before being fatally shot himself.

As Season 3 opens Sunday (June 19), on PBS’ “Masterpiece Mystery!” (check local listings), in the world of the show it’s March 1967, a couple of months later. Morse has been released from custody but remains on suspension pending a full investigation. In a move fairly typical of the historical period, officials have decided it would be in the greater public interest not to release full details about the sordid scandal, but the worst apples — including some of Morse’s old nemeses — have been booted off the force.

That’s cold comfort to the young detective constable, however, whose passion for law enforcement has been shaken to its core.

“He is completely disenfranchised with the police force,” Evans tells Zap2it. “And who wouldn’t be, frankly? He’s been stabbed, shot at, imprisoned, so now he’s taking time out with some other pals away from the police force and his usual routine.

“He falls in with this group of people who are very, very different, very wealthy, different morals. It’s like in life when sometimes major things happen and you think, ‘You know what? Maybe this is an opportunity to reinvent myself into something new.’ ”

An old friend invites Morse to a party at a lakeside estate near the rustic cottage where Morse is weighing his career options. There he meets several posh characters, including the charismatic and charming Joss Bixby (guest star David Oakes, “The Borgias”), who find this new arrival as fascinating as a unicorn. Thursday and Morse’s other colleagues on the force take a very dim view of these new acquaintances, but after a member of this charmed circle is killed, Morse inevitably finds himself drawn back into his former life of investigation.

“It’s like fate keeps pulling this person back to the force,” Evans says, “so this episode is really about him trying to make his peace with that.”

That’s not a spoiler. Given that “Endeavour” is a prequel to the long-running classic mystery series “Inspector Morse,” even as we watch the main character waffling about his future, we never doubt Morse will return to sleuthing. The question lies only in the how and the when.

In Season 3, Morse finally gets overdue respect from his peers and bosses on the force, a turn of events that pretty much had to happen, given Morse’s impressive record of solving fiendishly difficult cases.

“This person has solved all of these crimes in one sort of odd, intuitive, intelligent way or another,” Evans says. “It stands to reason that the other people might say, ‘Hold on a minute. Maybe we should keep this person around.’ Eventually you wouldn’t stay with a job if you knew you were integral to something but weren’t being appreciated and respected. There will be conflict, obviously, because there has to be, but it can’t be the same conflict all the time. That would turn into a joke.”

This season also sees the arrival of an appealing newcomer, Woman Police Constable Shirley Trewlove (Dakota Blue Richards, “The Golden Compass”). When we first meet her, the character is clearly professionally smitten with Morse’s police work.

“That’s definitely true, but I think it also bears mentioning that this new character is interesting in her own right, aside and apart from Morse,” Evans says. “She’s a woman in her mid- to late 20s in the ’60s who is joining the police force. She’s very, very bright and a really good-looking woman as well, but she’s not willing to use that. I’m not entirely sure where they will go with that — although I have an idea — but I doubt they will end up together because of what we know about Morse (in his later years). There definitely is a recognition of a mutual intelligence between those two characters.”

Posted by:John Crook