PRETTY LITTLE LIARS. 8 tonight, ABC Family.

"FRIENDS share secrets. That's what keeps us close."

Those are some of the last words Alison DiLaurentis (Sasha Pieterse) speaks to her four closest friends before she disappears forever.

Or are they her last words?

And is she really gone?

AS ABC Family's "Pretty Little Liars" premieres tonight, no one seems sure.

Set in fictional Rosewood, Pa., somewhere on our very own Main Line and based on a series of teen novels written by Sara Shepard for the company behind the CW's "Gossip Girl" and several other teen-centered book/TV/movie collaborations, the show opens with an apparently manipulative young girl's disappearance and then flashes forward a year to find the clique she once headed is no longer clicking.

At least not until its members begin receiving texts and e-mails from someone who seems to know all their secrets and signs each taunting missive "A."

Could there indeed be texts after death? And what's that going to cost us?

Yes, that's a mother question, one that should probably have no place in a review of a show aimed squarely at girls young enough to be my sons' non-existent younger sisters.

But I am what I am, and as I watched this mystery about pretty, well-off girls and their missing friend, I remembered that one of the things I am is a huge fan of the late, great "Veronica Mars," which covered a lot of this ground before, and more cleverly.

Still, one has only to comb the adult best-seller lists to know that the drama of the missing or murdered child remains central to our storytelling for all ages. "Pretty Little Liars" is entitled to its version.

If only it could have resisted some of the other cliches.

I mean, who doesn't know that if you meet an attractive stranger the night before starting some important new enterprise, that person is just about guaranteed to reappear in your life in the most inconvenient of ways before the sun sets the following day?

But then maybe young Aria ("Privileged's" Lucy Hale) never saw "Grey's Anatomy." Or "Dawson's Creek."

One of the hazards of middle age is that doctors and your kids' teachers begin to look like teenagers. Meanwhile, on television, teenagers - or at least teenage girls - all appear to be in their 20s.

If not older.

No need to adjust your set here: They may be playing high schoolers, but in the grand tradition of the WB and CW, some of these "Pretty Little Liars" are old enough to have graduated by now.

Yet Pieterse, who plays a character who'll likely be seen only in flashbacks, is reportedly just 14, making her not only age-appropriate but as much as a decade younger than Troian Bellisario, who plays smart girl Spencer and whose IMDB.com entry, at least, lists her as 24.

Not that I can blame Bellisario, there apparently being only one place for an actress on a show like this once she's considered too old for prom. Which is how Holly Marie Combs ("Charmed") and Laura Leighton ("Melrose Place") ended up here playing mothers of girls just about young enough to be their pretty little (lying) daughters.

Ready, aim, record

"Justified" (10 p.m., FX) wraps up its first season tonight in a not-to-be-missed episode, "Bulletville," that's scheduled to run about 4 minutes long.

So if you're time-shifting, set your sights accordingly. *

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