Ever since the terrorist attacks of 2001, American firefighters, who suffered such terrible losses in the collapse of the World Trade Center, have been accorded greater respect than ever before. This is saying something, for firefighting has always been a business that ordinary people have looked up to with appreciation bordering on awe. Zac Unger puts it nicely when he describes the thoughts that went through his mind as he prepared to apply for a firefighting job in Oakland, California.

"I knew that firemen put out fires. I knew that it was dangerous and exhausting. I knew that they worked hard and that they always seemed to be laughing when I saw them in the store or washing the rig on the sidewalk. I knew that they saved people's lives, and once I started thinking of myself in that role, no matter how far off it still was, it seemed impossible to imagine doing anything else. How could I go back to wandering blithely through [another job] when there were people trapped in burning buildings? How could I sit on a rock and watch some bird do its thing when there were parents who needed me to carry their babies down ladders before I wiped the soot out of my face and said 'just doing my job, ma'am,' then walked back into the smoke? The imaginary hero that I had been as a kid was getting antsy, ready for the real thing."

Unger was an unlikely candidate for the firehouse. He was a native of Oakland, to be sure, but he'd grown up in a relatively privileged neighborhood -- his father is a doctor, his mother a teacher -- and had "always attended earnest, progressive day schools where everyone was made to feel cuddly and special," where at recess "we ate teeth-shattering banana chips and drank cloudy apple juice before returning to our cooperative, non-violent games." He had attended Brown University and the University of California at Berkeley, and had worked at "a series of odd and isolating jobs" with a "vague plan" of entering forestry in one way or another.

Unlike most of the others in his recruit class of 21 men and three women, he had an interest in firefighting that "had started out as a lark," a way of satisfying his longing for challenge and adventure. There's no reason to believe he was slumming, or to suspect he had it in mind all along to write this book, but he clearly had other options -- more conventional, less dangerous, more remunerative -- to which he could turn. He wasn't George Plimpton playing at being a pro-football quarterback, knowing that in the end he'd be back in his tony Manhattan apartment, but at least at the beginning it must have been a bit hard to take him seriously.

The reader who begins "Working Fire" with skepticism will find that it quickly dissipates. The book works on two levels: as an inside view of firefighting that vividly re-creates the excitement and fear intrinsic to it, and as an account of how a son of the flower-power class turned into the real thing, a passionately dedicated firefighter. It doesn't hurt that Unger is a lucid writer whose prose almost always is set at just the right pitch, something that all too many professional writers often fail to achieve.

Unger entered firefighter training in the late 1990s, when he was in his mid-twenties. His stint at the academy lasted 16 weeks, during which he was pushed to the limit, though he doesn't seem to have had serious notions of calling it quits. His drill instructor, Capt. Gold, had him on the ropes over and over, but he persevered: "I'd shed my flaky hippie skin and ducked into a heavy turnout coat unscathed. I was surprised to find myself loving Gold's paramilitary rigor. Everything was so clear, so black and white, so fire and water. With Gold I always knew exactly where I stood; there were no gray areas, no problems to be worked through, no feelings to be endlessly processed."

After the academy came probation, which "is designed to keep the new kid on edge," moving from firehouse to firehouse to get full exposure to the broad range of challenges with which a big, urban fire department must contend. He learned to take the ribbing he got from senior firefighters, to close his mouth and do the job: "Better just to work hard, shut the hell up, and let the barbs float past. A new kid should be seen and not heard." But the lure of firefighting had caught him, and he was "impatient ... to start living the dream." Before long the dream came true, and he knew the thrill of the moment when "I'm riding on a fire engine and there's smoke in the air." This passage deserves extensive quotation.

"That's the moment when it all comes together for me, when everything makes sense and I wish that anyone who ever wondered why I wanted to be a firefighter could see me now. When the rig is gleaming clean and you step off while snugging your helmet onto your head as you kick the ax up smoothly and slip it down into its spot on your hip like a gunslinger. It's all worth it then -- the dead guy in the hallway that morning, the petty hassles with admin, the pain in your back that seems to be there every day now. Because you're a fireman, the closest thing there is in this world to being a superhero. And when it's good, riding the rig is like flying. All the other drivers are pulled off to the side in their cars, and the siren is screaming, and kids are waving. And you cut through the streets like a dolphin through water, dodging, playing, slipping back and forth from one side of the road to the other, snaking around concrete islands, slowing a little at the lights and then powering right through with a heavy foot on the horn pedal. That's what being a fireman is all about."

Well, let's say a big part of it. Other parts don't arouse quite so much youthful exuberance: finding oneself trapped in a smoke-clotted basement, dashing off to one false alarm after another, failing to save someone from death. Because he's a paramedic as well as a firefighter, Unger runs into plenty of people "who exist on the fringes of death," and is more affected by them than by those who die: "Kids with rat bites. Heroin addicts who haven't left their pitch-black tenement hotel rooms for years. Diabetics so ill informed or apathetic about their condition that they have to undergo multiple amputations, slowly losing their limbs inch by inch as their circulation deteriorates."

Many people don't realize that a significant percentage of the calls that any firehouse gets are not for fires but for medical emergencies. In a city such as Oakland, with large impoverished neighborhoods and serious drug problems, firefighters are as much in the business of rescuing and healing as that of extinguishing fires. If there's an aspect of his job that Unger at times finds difficult to bear, this is it.