"33" is a relentless hour of riveting television empathy, where by the end you will know what it feels like to be threatened with a Cylon attack every 33 minutes for five straight days, having had little or no sleep.

You will also come to know, without any doubt, the gravity of the situation, in which humanity is down to its last gasp, on the run, with the looming possibility that the entire survival of the race depends on the fleet's successful execution of the next FTL (faster than light) jump cycle in 33 minutes.

On Colonial One, President Roslin has a white board with the "head count" written in dry-erase marker, which stands at just below 50,000. She makes revisions throughout the episode -- mostly downward -- to reflect the new survivor count as the latest casualty reports come in.

Yes, "33" is most definitely grim and heavy, exhausting and unremitting -- and quite powerful. If you're not interested in going to a fairly dark place, this will not likely be your cup of tea. Here's a story that believes with utter conviction what it's conveying. It feels like it is actually happening -- rare, for an hour of television. Filmed nearly a year later, the story takes place almost immediately after the events of the miniseries/pilot. As a follow-up to the events of that story, in which the 12 colonies were attacked and the handful of survivors were forced to flee, it grabs you by the throat and doesn't let go. It's the necessary miniseries epilogue that shows what is at stake.

The teaser sequence is a tour de force of execution -- a masterpiece of tone wonderfully directed by Michael Rymer, who also superbly directed the pilot. It balances action/suspense, functional dialog, strong images, and intriguing levels of wakefulness. The Galactica crew has gone 130 straight hours without sleep, and it shows. The Viper pilots, on patrol for Cylon Raiders, struggle to keep their eyes open. Baltar sits in a passenger seat on Colonial One, drifting between half-asleep and half-awake. Analog clocks tick toward the deadline of 33 minutes: tick, tick, tick. The sound echoes through Baltar's dreamscape. Sometimes he's awake in the midst of that dream, talking to Number Six as if she were sitting next to him. Sometimes he's in fantasy mode, back at his house on Caprica. Dreaming, awake -- is there even a difference for him? "There are limits to the human body, the human mind," he says. One could say he's already passed his, talking out loud to an imaginary woman.

A Cylon base star appears. It's a frightening sight, with a foreboding shape, like some sort of sea predator. The fleet jumps away, safe for another 33 minutes. The clock is restarted: tick, tick, tick. Between jump cycles, the crew has 33 minutes to make preparations for the next jump -- and to think about whether the Cylons will find them again.

In the pilots' ready room, strategic plans are discussed for the next jump -- but hell, Apollo says, you don't need to hear these plans again, because you've already been through this 237 straight times. As the pilots exit the room, they affectionately touch a photo on the wall. It has a soldier in the foreground, his back to the camera, and destruction in front of him. The exact context of the photo is never explained, for which I'm glad, because it doesn't need to be. We understand the emotions completely. These people are still grieving for the fallen colonies of Kobol. It's a poignant moment, and exposition could probably only have lessened its impact.

Even more poignant is a scene in the corridors: hundreds, maybe thousands, of makeshift memorials. It reminded me of 9/11, when people posted photos of their missing loved ones along the streets in New York, hoping they would come home.

This episode is somber but not sentimental, serious but not funereal. It has a plot, and it has moments of real suspense. But it does not cheat its premise, and it does not let anyone off the hook.

In the Viper hangar, Kara blows up at Lee because he doesn't reprimand her for insubordination ("We're not friends; you're the CAG"). She starts to laugh and cry simultaneously, which can't be a good sign of mental health. Usually when that happens, you're probably under more stress than you know what to do with.

The plot is simply: How do we escape the Cylons, who are somehow tracking us to our new position with each jump? But the plot is also about a man named Dr. Amarak, a passenger on the luxury liner Olympic Carrier, who knows Baltar from the Colonial Ministry of Defense, and tells President Roslin that he has an urgent message about a "traitor in our midst." Just hearing the name Amarak throws Baltar into a state of internal panic: Did Amarak find out that I gave Six access to the defense mainframe? Baltar, ever the self-preservationist, instantly begins thinking of ways to get out of this jam.

A minor mix-up in CIC causes the Olympic Carrier to be left behind when the fleet makes the jump. Dualla (Kandyse McClure) can't account for it, and it may have been her mistake. Under the circumstances, where pilots are popping stimulants like candy and most people are walking zombies, the error seems understandable. But, on the other hand, there were 1,345 people aboard the Olympic Carrier, now presumably dead or captured by the Cylons. Colonel Tigh has a brief speech about the need for performance under these pressures, but I like even better the understated simplicity of Adama's speech: "We make mistakes, people die. There aren't many of us left." No wasted words or raised voice, because the facts of that statement carry all the weight, and additional emphasis is unnecessary.

The plot thickens: After 33 minutes, there is no Cylon assault. Adama suspects that perhaps the Cylons were tracking the Olympic Carrier -- or perhaps a Cylon agent on board the Olympic was giving away their position. A while later, the Olympic reappears, which proves to be a test of Adama's theory on the Cylons' all-too-adept pursuit skills. Did the Cylons let them escape deliberately? What other explanation can there be?

Baltar's stake in this is amusingly self-serving. When the Olympic vanishes, Six calls it a miracle that God has granted him. When the Olympic resurfaces, Six tells him that it's God's punishment for his lack of faith. Baltar, a staunch atheist, begins rethinking that stance. The religious debate between Baltar and Six (or perhaps we should say the imagined debate inside Baltar's head) is interesting, but what's even more interesting is how Baltar ultimately decides to find religion for purely self-serving reasons. He repents his sins in the hope that the Olympic Carrier will be destroyed such that he can be saved.

The fate of the Olympic, by the way, makes for a riveting sequence of its own. With the suspicion that the ship has been compromised, and the realization that the Cylons are again just minutes from another assault, and the detection of nuclear weapons on board the Olympic, the Galactica attempts to stop the Olympic from approaching the fleet. The Olympic runs the blockade and doesn't acknowledge orders to stop, leading to an unthinkable decision on which Adama and Roslin both concur and Apollo must carry out: Destroy the Olympic Carrier.

Visually, this plays out with a compelling you-are-there believability, as the camera peers into the windows of the ship (seeing no people, Apollo and Starbuck speculate the ship is empty) and then shows final shots from Apollo's point of view before he pulls the trigger and destroys the ship. I really hate to bring up 9/11 again, but on that day there was talk that shooting down commercial airliners might've been necessary if they'd been known to have been hijacked, and this scene plays out how we imagine such a scenario might've felt for a military pilot.

The subplot of "33" takes place on Cylon-occupied Caprica, where Helo is on the run from the Cylons, after having volunteered to be left behind several days earlier when Sharon returned to Galactica with their Raptor. This left me wondering how he survived, and what happened to all the other civilian survivors who were present at that scene. I guess I'll save those questions for another day, since that's what "33" does. A copy of Sharon shows up and rescues Helo, claiming that she returned to Caprica for him. The opening prelude to Battlestar Galactica says the Cylons "have a plan," and it would seem Helo is a part of this plan.

The episode ends on a necessary note of hope (a baby is born, leading the "head count" to increase by one), signaling that perhaps after this grueling test of survival, a corner has been turned and things will get better. "33" is excellent television drama. If the series can stay this good, it will be TV viewing time well spent.

Irrelevant footnote: The way Edward James Olmos says "previously on Battlestar Galactica" at the beginning kicks ass. He should say it every week.

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