The sight is a familiar one for “24” fans: Counterterrorist agent Jack Bauer (Kiefer Sutherland) sits panting, handcuffed to a chair as he’s tortured by non-descript Middle-Eastern men. How will he get out of it this time? After a phone call prevents the leader from cutting off Jack’s fingers, only one guard is left. With a vicious plunge and menacing eyes, Bauer digs his teeth into the guard’s neck. The guard falls, and Jack spits out a chunk of flesh, blood dripping down his chin. So ends the first hour of Season 6 of Fox’s painfully addictive terrorism drama.

After five seasons and 136 deaths by Bauer’s hand alone — according to bauercount.com, which features video of and details about each killing — there are few ways to end a life that haven’t already been employed. At this point, Jack ranks somewhere between God and Mike Tyson on the list of people you don’t want to piss off. But the show hasn’t worn out its welcome: Season 5 of “24” was the strongest season ratings-wise. Not only did it win an Emmy for Best Drama, but the very scientific Facebook Pulse feature ranks “24” as the third most popular TV show at Yale.

The four-hour season premiere aired during the first two nights of the semester. The show’s principal appeal — the sense that anything can happen, a precedent established with the murder of Jack’s wife by his closest colleague and ex-lover in the closing moments of the first season — remains intact: The controversial death of Jack’s partner, Curtis Manning, and the haunting detonation of the “suitcase nuke” showed that “24” could match the intensity of last season.

But only on “24” could a nuclear bomb and a carnivorous slaying be overshadowed by a singular image — Jack Bauer collapsed, throwing up — a reminder that Season 6 is a story about Jack, a character study about coping with extreme sacrifices.

Two years spent being tortured, without speaking a word, takes a toll even on Jack. He claims, “I don’t know how to do this anymore.” Toward the end of the fourth hour, Jack kills his partner to save the life of a terrorist vital to the investigation, a killing which causes Jack’s physical breakdown. As he attempts to resign from CTU, he sees a mushroom cloud blooming miles away. Jack’s face watching the cloud — the odd mixture of disgust, resignation and determination — is unforgettable.

The choices he is forced to make, between friends and enemies, family and national security, are more poignant than ever. Although each season chronicles a single day, the writers never forsake insight for action; for example, they daringly ended the third season with a prolonged scene of Jack sobbing in his car. Sutherland shows he’s up for the challenge, as his performance in the premiere was his best to date.

In the fifth hour, the writers upped the stakes for Jack even further by bringing his blood relatives — his father (James Cromwell) will be introduced in the sixth hour and last season’s evil bald mastermind was exposed as Jack’s brother Graem (Paul McCrane) — into the picture for the first time. Side note: It can’t be coincidence that Graem’s son looks exactly like Jack and Graem’s wife “was still not over Jack” when she got married.

The role of Wayne Palmer (D.B. Woodside DRA ’96) — a new president struggling to step out of his late brother’s shadow — this season is the latest in “24”’s thoughtful commentary on the unchecked power the presidency has amassed over the years, commentary that elevates “24” from simple thriller to important, provocative show. David Palmer’s (Dennis Haysbert) term highlighted the danger of personal connections and John Keeler’s (Geoff Pierson) the flaws in the chain of command. It appears that the term of the younger Palmer, who is clearly the Bobby to David’s JFK, will exemplify how much power the Karl Roves of the world have.

“24” transitions between the Oval Office and small office politics seamlessly. Fan favorite Chloe’s (Mary Lynn Rajskub) plot, involving mediating between an ex-boyfriend and an ex-husband, actually fell surprisingly flat in the premiere, despite her uncharacteristically chic hairdo, as both men are just annoying. Thankfully — another merit of “24”’s format — the action moves so fast that all three characters will be in dramatically different situations in a few hours time.

Sutherland has all but confirmed a “24” movie to follow this season, meaning the stakes are even higher. Celebrated TV shows rarely transfer to the cineplex successfully, but, of course, if “24” has taught us one thing, it’s that anything can happen.