More's not necessarily merrier as a serial killer joins 'The Killing'

* THE KILLING. 8 p.m. Sunday, AMC.

BE CAREFUL what you wish for.

If you were frustrated before by AMC's "The Killing" - two seasons to solve one teenage girl's murder! - then a 12-episode season that everyone involved supposedly pinky-swears will resolve multiple murders has to be a drama junkie's dream, right?

Except, of course, that this means that detectives Sarah Linden (Mireille Enos) and Stephen Holder (Joel Kinnaman) are tracking a serial killer.

Serial killers are too well-represented on television to guarantee that Season 3 of "The Killing" will be as distinctive as the Seattle-set drama once appeared to be, back before a red herring or two too many turned the show - adapted by Veena Sud from a widely praised Danish series - into a serial killer of a different kind.

If I sound bitter, it's not, believe me, because viewers had to wait an extra season to find out who killed Rosie Larsen. (Given the ratings for Season 2, I'd say plenty had forgotten the original question by then.) What I hated was seeing how fast a promising pilot could go downhill.

So having screened only the two back-to-back episodes that AMC will premiere Sunday, I'm reluctant to lose my heart again, much less encourage anyone to follow me down what could be a dead end.

And yet I'm intrigued.

Because Sud, who created the story line for this season, has decided to set Linden and Holder on a search for the kind of predator who might lack the panache of a Hannibal Lecter but gets away with murder, time after time, by killing those no one will miss.

Except that if this season of "The Killing" doesn't lose focus, viewers will care about what happens to the teenage runaways whom Sud introduces, especially Bullet (Bex Taylor-Klaus) and Kallie (Cate Sproule).

First, though, they'll have to remember to care about Linden, who, more than a year after the Rosie Larsen case ended, has left the police department and is living on an island in Puget Sound, working a mininum-wage job for the local ferry.

She's quit smoking, she has a hot, younger boyfriend and she's wearing clothing that's not several sizes too large. So you know that can't last.

Holder, meanwhile, has started dressing like a grown-up and studying for the sergeant's exam. When he looks up Linden to talk about one of her old cases - for which a man was sentenced to die - he ends up reopening some old, ugly wounds.

Which brings us to Peter Sarsgaard ("An Education"). Sarsgaard plays Death Row inmate Ray Seward, who, thanks to his insistence on getting it over with, has just 30 days to live.

If one of his guards doesn't kill him first.

Seward's undeniably a monster, but is he the right monster?

More important, will Sarsgaard, who does creepy to a fare-thee-well, draw too much focus from the kids whose stories might separate "The Killing" from all those other serial-killer stories?

By the second hour, which ends in a scene that, frankly, left me more confused than I think I was supposed to be, I had a lot more questions.

And like Linden, I was feeling I might need to stick around a while longer to get some answers.