What we are discovering in the third season of 24 is that if you set up a series in which anything can happen, anything will, whether it makes sense or not. Thus, we now find our hero, Kiefer Sutherland's government agent Jack Bauer -- the epitome of hardheaded discipline -- apparently a junkie trying to shake a drug addiction born of loneliness, torture (both inner and outer), and the soul-sapping realization that he's aligned himself with David Palmer (Dennis Haysbert), the only U.S. president with more personal problems than Bill Clinton. Oh, and I say ''apparently'' to cover my tail, since in any given hour, ticktocked by the minute in each episode, plots and motives are overturned for the sake of unexpectedness. In fact, please consider all speculations in this review as being prefaced by ''apparently.'' For example, as I write this, Jack's smack habit could, for all we know, prove to be a devilish ruse. In any case, it cannot hold much allure for Nina Myers (Sarah Clarke), the former lover who murdered his wife. You got the feeling they recently smooched primarily as an alternative to killing each other.
If the biggest surprises of the current ''24'' scenario are that Jack's cougar-bait daughter, Kim (Elisha Cuthbert), suddenly has enough brains to hold down a sensitive position at the Counter Terrorist Unit and switch to a new hairstylist, its biggest letdown is that the series is locked into yet another foreign-bad-guys blackmail scheme. Set three years after last season's foreign-bad-guys blackmail scheme, the central premise involves some kind of virus that can either kill you or do nothing to you: Within the first three hours this season, a character exposed to a powder thought to contain the virus prompted a ''level 3 hot zone'' alert and forced Jack to wear one of those clumpy, very nonheroic-looking hazmat suits. But, this being a series in which we know there are 24 hours to fill, no third-hour threat can mean much -- the powder wasn't dangerous after all; the virus went elsewhere.
This is now the problem with ''24'': The first season was a giddy novelty; the second season was a guaranteed tune-in to see if the producers could pull off the same trick twice. But now we know the rhythm of the series, and so its anything-can-happen energy has dissipated into a how-can-we-bring-back-fan-favorites waiting game, proved by the simultaneously welcome yet predictable return of Nina and President Palmer's evil ex, Sherry (Penny Johnson Jerald). The series, which initially grappled with terrorism in the wake of Sept. 11, has doggedly stuck to making sure that the main enemy always has an accent (this season, it's a couple of Mexico-based baddies, the Salazar brothers) and an aim to make some big bucks by assaulting America.
Clearly -- or actually, the way ''24'' does it, cloudily -- the virus is what Alfred Hitchcock used to call a MacGuffin: an urgent-sounding item that sets everyone in motion but which is ultimately irrelevant. ''24'' is always about the process of getting Sutherland and one or two supporting players (this season, a buzz-cut side of CTU beef played by James Badge Dale) into some insurmountable trap, preferably one that involves torture and a few gunshot wounds. And there must be at least one scene per season in which Jack kills someone ruthlessly, as when, handcuffed in the Dec. 9 episode, he scissor-locked his legs around a prison guard in a very cool, death-dealing swivel. (Has Fox found the 18 -- 49 S&M market particularly lucrative?) Then we wait a week and the good guys wriggle out of their traps. Some characters disappear -- I'm sorry, where did Andrea Thompson, introduced early on in her first post -- I'm-no-actor-I'm-a-TV- journalist acting role, go to? -- while others begin to loom larger.
So far, my favorite by far is Chloe, the perpetually frowning CTU computer geek played by Mary Lynn Rajskub, formerly a perpetually frowning assistant on ''The Larry Sanders Show.'' Chloe is the kind of humorless drone another character can blithely refer to as ''a pain in the ass'' and who does patently stupid things like bringing a baby into the CTU office in midcrisis time because her nanny had to leave early. Chloe is a wonderful creation who'll turn out to be a stealth villain or a walking MacGuffin. Either way, Jack should, like any good torture-enduring middle manager, be paying less attention to the boss (i.e., the President) and more to his underlings -- the bitter, resentful employees without good day care! But Jack can never learn this lesson, because if he did, the clock would stop on ''24.''