* BOSS. 10 tonight, Starz.

* APPROPRIATE ADULT. 10 p.m. tomorrow, Sundance Channel.

* STEPHEN KING'S BAG OF BONES. 9 p.m. Sunday and Monday.

HORROR FANS who haven't become jaded by the never-ending bloodbath on FX's "American Horror Story" have probably already marked their calendars for "Stephen King's Bag of Bones," a two-parter that begins Sunday on A&E.

But while there are a dependable number of shivers in this latest King adaptation, which stars Pierce Brosnan as a widowed writer who finds himself embroiled in a custody dispute with the usual very dark overtones, it's not even close to being the most terrifying thing you could see on TV this weekend.

That honor goes to either tonight's season finale of Starz's "Boss" or to the Sundance Channel's presentation of "Appropriate Adult," a film about an infamous British case in which a serial killer developed an unusual bond with the woman assigned to monitor his interrogations.

Both of them, frankly, scared me silly.

For those who haven't been keeping up with the post-sitcom Kelsey Grammer, he's currently the boss of "Boss," a drama about a fictional Chicago mayor struggling to keep his grip on power while concealing a neurological condition that's sooner or later going to take him down for good.

Grammer's Tom Kane has probably never been a good guy, but illness seems to have only made him worse. Tonight's episode is best summed up by the mayor himself, as he warns: "By the time this day ends, every person who has plotted against me will feel the force of my wrath."

Yep, he really talks like that. All the time. Sometimes even to people only he sees.

It's a testament, perhaps, to Mario Van Peebles' direction that the speechifying didn't blunt the impact of all that vengeance, which plays out at on an operatic level that would satisfy all but the most bloodthirsty fans of "The Sopranos."

And it ends with a haunting image that might have made a fitting coda to the show, had Starz not ordered a second season before the first even debuted.

There's not a lot of high-flown language in "Appropriate Adult," a film that was reportedly controversial in Britain, where some felt it exploited an infamous case in a way that could only bring pain to the victims' families.

Here, where far fewer of us know much about Fred West or his wife (and sometimes accomplice), Rose, the first shock is likely to be seeing Dominic West (no relation, one hopes), of HBO's "The Wire" and BBC America's "The Hour," playing a man who speaks almost casually of cutting up his daughter's body and disposing of it in the trash.

Emily Watson plays Janet Leach, a social worker who's West's "appropriate adult" - a person who, in Britain's legal system, is brought in to act as a kind of witness for suspects who are either underage, or as in the case of West, might be considered not totally capable of understanding the legal process.

It's an odd angle on an even odder case, one that's gradually revealed to be more and more horrific. (But then my experience probably differed from that of viewers already familiar with the more salacious details.) The only thing that makes watching this story unfold even slightly bearable are West and Watson's performances.

If you make it through that, though, "Bag of Bones" should let you sleep in relative peace, if only because, like most of King's work, it's at least faithful to its own internal logic.

OK, so I did wonder why Brosnan's Mike Noonan has an Irish accent and his brother doesn't.

Or why a childless couple would happen to have alphabet magnets on their refrigerator.

But compared with (sigh) "American Horror Story," the tale itself makes a certain amount of sense and like any good thrill ride, spaces out the scary parts just enough to make them truly scary.

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