Though there has been little movement on the issue so far, when he was on the campaign trail, President Barack Obama promised to finally embark on transformative immigration reform during his first term — a task that twice eluded his predecessor.

The reasons to do so are numerous: national security and economic stability, to name two. But as rhetoric flies back and forth, few mention, or even know much about, the experience of illegal immigrants themselves.

That’s because, as author Gabriel Thompson puts it, they’re “Working in the Shadows,” which is the title of his new book. The premise, as the subtitle states, is “A Year of Working the Jobs (Most) Americans Won’t Do.”

Thompson, a journalist and former community organizer, embarks on a yearlong quest to delve into the immigrant experience. He goes undercover in three different jobs for a few months each; first he picks lettuce in fields in Yuma, Ariz., then heads to Russellville, Ala., for work in a poultry plant, and finally returns to his hometown, New York City, to toil as a bicycle deliveryman.

Each job comes with its individual challenges. Standing all day in the lettuce fields takes a toll on the body, but the work is tolerable. The workers eat tacos for lunch together and sing songs on their breaks.

Tearing chicken parts and carrying buckets of bloody gizzards, on the other hand, is disgusting and unsatisfying. The loud mechanical whir of the plant makes it hard to talk to others, so the job basically entails repeating the same motion over and over in silence — a feat that dulls the mind.

Delivering food on bike is fast-paced and strenuous. Navigating the streets of New York while balancing seven food orders on the handlebars (and dodging taxis) is no easy task.

But for all their distinction, the jobs have much in common. And so what Thompson shows us with his fine work of immersion journalism is exactly what we expect to see: The work done by illegal immigrants is backbreaking, mind-numbing and low-paying. They are often subjugated physically and economically, yet they return day in and day out to try to make a better life for themselves and their families.

Thompson pursues work done mostly by Latino immigrants, but he doesn’t try to “walk in their shoes,” as he clearly states in the introduction. His experiment, rather, is to find out whether he can stand the work. And so it’s really more of a tale of his journey, with personal asides about every pain in his hands and back as he cuts lettuce stalks, every impulse to strangle his overbearing boss at the poultry plant and even the problem of actually securing and keeping his job (he twice gets fired).

Along the way, though, he meets dozens of characters emblematic of the immigrant experience, and since he can speak Spanish, he learns much conversing with them.

There’s Sabrina in Russellville who came to America from Mexico City to follow her dream of starting a diner. Pedro is a stern but even-handed boss in the lettuce fields of Yuma who manages his team with dignity. Alvaro, a middle-aged man from the Galapagos Islands, works 14-hour days washing dishes at two different restaurants in New York — despite the fact he regularly gets shorted hours.

In Yuma, most of the Dole lettuce-picking staff is composed of guest workers who live just across the border in Mexico. But in the Pilgrim’s Pride plant in Alabama, only a third are Hispanic (mostly from Guatemala). And so an auxiliary discovery for Thompson is the degree to which American citizens are subject to the same rural poverty, working grueling jobs and trying to support families on often little more than $8 an hour.

Thompson unabashedly views his task through a liberal lens. He routinely complains about the lack of organized union support among immigrant-heavy industries, and animal cruelty concerns are ever-present during his poultry workdays. He decries workplace immigration raids and says immigrants should be offered a path to citizenship. To conclude, he calls for grass-roots support to help pass upcoming Obama administration immigration reform.

So those in favor of Democratic-led reform on the issue will find this book appealing. But even those on the other side of the debate will find this a worthy read for its insight into not simply immigrant labor, but also the psyche of the liberal case for immigration reform.

As the debate over how to solve our immigration problem ramps up perhaps this year or the next, look for “Working in the Shadows” to be cited by political types on both sides as proof positive that the United States needs comprehensive immigration reform.