Who killed Rosie Larsen? When AMC’s “The Killing” began its first season, it was the question, we were told, that would soon consume us. To the degree that it actually did, the show’s audience practically staged an armed revolt and that first season ended on a cliff and left the murderer of Rosie Larsen dangling into a dense, impenetrable cloud of overplotted uncertainty.

It was one of the classic moments of television hubris and perfidy of the past couple of decades – right up there with David Chase’s clever but infuriating decision to end “The Sopranos” forever by giving us the Tony’s-eye-view of what it’s like to be shot in the head while having a nice meal with the family in suburban New Jersey.

By the time the murderer of Rosie Larsen was revealed at the end of “The Killing’s” Season 2, those of us who were still watching the show found it to be such an anticlimactic contrivance that the supposed shock of it all seemed like the kind of unfortunate family dysfunction that gets 90 seconds on the local 11 o’clock news. And that’s despite all the political shenanigans and Native American reservations involved.

A funny thing had happened, though, to the AMC show by that time: “Killing” loyalists just didn’t give a fig who killed Rosie Larsen. We knew a Hitchcock plot Macguffin when one kept smacking us in the face weekly. We’d moved on to the real, if paradoxical, charisma of the show that had conned us: the seasonal affective disorder of two homicide cops whose reaction to Seattle’s constant rain and gray weather was escalating obsession and alienation.

Tiny Sarah Linden (Mireille Enos) and her partner Holder (Joel Kinnaman) had become one of the most unconventionally appealing tandems in all of television – a weekly test of mutual understanding and tolerance. One cop was a druggie rule breaker. The other was an obsessive cop but careless mother. You didn’t need to be a shrink to find their attitudes toward their job extremely unhealthy.

But their disparate avenues to ill health fit together nicely. And that’s what kept us watching – as well as several layers of Seattle society affected in different ways by Rosie’s death, not least a self-adoring local pol (Billy Campbell) and his sexy manipulator (Kristin Lehman.)

People were hooked on “The Killing.” Really hooked. Despite the first season’s climactic calamity, people stayed with these two, drawn in by the AMC acting style which was, in general, to eschew unnecessary drama in performance, even in plot moments that seem to cry out for it.

“The Killing” is back on AMC at 8 p.m. today. What we are promised for the show’s third season is Sarah Linden leading an ostensibly “normal” life off the force but getting seduced back into partnership with Holder by a serial-killing case that relates to her past.

Creator Veena Sud – wisely – promises “you don’t have to have seen season 1 and 2.” She also promises the involvement of street kids for sale and a monster killer in jail played by Peter Sarsgaard. In other words, “The Killing” is out of the business of peeling off political layers in Seattle. It’s now in the business of turning into just another series spun off from the world of quirky serial killers so memorably introduced to American mythology by Thomas Harris in his novel “Red Dragon.”

“The Killing” has been a trial to its fans since its first season. In what they claim are whole new ways of submerging its overcast cops in different kinds of internal weather, we have to be ready to get hooked again. And annoyed.

Which, of course, is where “The Killing’s” more famous and acclaimed Sunday evening brother on AMC – “Mad Men” – continues to be in American life, despite now having moved from the early ’60s Kennedy era to the late-’60s era of political assassinations, street rebellion and the Woodstock Festival just around the corner.

I’ve been watching “Mad Men” a lot this season – enough to know that from any point of view besides fan delusion, the show is in a fair amount of trouble.

I confirmed some of that with one of its earliest and strongest partisans, a colleague who reports that she and at least one friend have gotten almost as tired of Don Draper (Jon Hamm) as the show’s leading character has gotten of himself. Nor are they as enthralled with the late-’60s hold on those on Madison Avenue as they once were by the long-neglected early-’60s era that was, in its way, far more interesting.

My problem with “Mad Men” right from Day One is that for all its vaunted research about getting ashtrays and decor right, nothing about the show has felt historically accurate, even when it was the most factually checkable. In this season, the whole ad agency – twice its former size after a merger – should be on fire with the walloping emergence of youth as a hugely powerful new consumer group to be exploited by merry barracudas.

What was quaintly called “Women’s Liberation” was on the horizon and ready to transform both consumer taste and the national Thesaurus of Slogans.

It’s making all of Draper’s drunken upchuckings and one-night stands looking smaller and smaller. Former heroine Peggy (Elisabeth Moss) is now mistreating creative underlings and refusing to commit herself like a really, really Bad Boss in Training.

Joan (Christina Hendricks) – the show’s most startlingly original character, by far – has been seen less and less, a sure sign that the show’s writers created a character so much more interesting than they intended that they can’t begin to understand her anymore.

“Mad Men” isn’t going to hell in a hand basket. It’s just marking time in Purgatory and waiting to shrink off the screen entirely.

And yet, just as I did with “The Killing,” when it turned its audience into Sunday night masochists, I find myself watching characters that are now drawn very badly because they once were drawn very well.

“Mad Men” – like “The Killing” – has found the secret of the most literate American TV audience in its heart of hearts, where what lives is hope that something remarkable that people once saw will reappear and settle in for a long run.

Hope is what fandom is all about. Who knows that better than those of us who live in a city with the Bills and the Sabres?

You have no idea how righteous fans can feel dining on pure unadulterated hope from week to week.

That, in itself, feels a bit like triumph.