If you swore off McDonald's after reading Fast Food Nation, you can relax--Eric Schlosser's follow-up, Reefer Madness, won't force you to drop your joint.

Despite its title, Reefer Madness actually explores three segments of America's underground economy: marijuana, migrant labor and porn. While the black market has always been with us, Schlosser demonstrates its resurgence and chronicles its unintended and often catastrophic consequences.

The estimated scope of America's "shadow economy" is staggering, as much as $1.5 trillion in unreported income. Beyond "robbing"' government's coffers and exploiting workers, Schlosser argues, black markets are insidious because they obscure our true identity. "If the market does indeed embody the sum of all human wishes, then the secret ones are just as important as the ones that are openly displayed. Like the yin and yang, the mainstream and the underground are ultimately two sides of the same thing. To know a country," Schlosser concludes, "you must see it whole."

The book begins with its namesake, "Reefer Madness," spun from Schlosser's award-winning Atlantic Monthly articles. For all our "just say no" drug rhetoric, Americans have discreetly, overwhelmingly said yes. We are a nation of pot smokers and more, perhaps, a nation of pot growers--a cash crop many believe has overtaken corn as the nation's largest harvest.

Schlosser travels to America's "marijuana belt" to meet farmers-turned-pot growers who say they are responding to market forces. In this fascinating underworld we learn how pot blankets America's bread basket. Out of sight yet ubiquitous, it's grown indoors in vast hydroponic caches or secretly cultivated in rented storage units.

Yet if you're looking for explication on the uses of hemp or the many mind-expanding wonders of 4:20, Reefer Madness will harsh your mellow. There's too much at stake. Schlosser puts a human face on the drug war's casualties by introducing us to individuals whose lives have been destroyed by transgressions most Americans consider trivial. In stark terms, he stacks up America's drug laws against other criminal penalties. The comparison is sobering. Any given drug offense is subject to local, state and federal jurisdictions, and the same crime can be tried more than once.

Schlosser illustrates the inanity of U.S. drug policy by introducing us to Mark Young, a man serving a life sentence in Leavenworth for brokering the sale of 700 pounds of marijuana. Young stubbornly refused to cooperate with the authorities and implicate his friends, which would probably have reduced his sentence. With Young, Schlosser gives us an uncommon portrait--the unrepentant pot smoker and man of principle.

With equal deftness, Schlosser depicts the other side of the debate. U.S. Drug Enforcement Administration agent Steve White defies law-enforcement stereotypes, and Schlosser's inclusion of personal details, such as White's passion for collecting antique English toy soldiers, humanizes him. Schlosser depicts his characters as individuals, not scapegoats, and helps us to understand their role in a larger system.

The second section, "In the Strawberry Fields" unearths underground agricultural labor. The shortest section, sandwiched between drugs and sex, it would seem "Strawberry Fields" doesn't stand a chance. Yet Schlosser paints such a haunting portrait of those caught in the market's margins that the section succeeds against these odds.

Drawing together immigration law, political obfuscation and plain old greed, Schlosser illustrates how strawberry pickers' union attempts were derailed by big business-funded decoy unions, and how impoverished workers from remote Mexican villages pay the price for globalization. As in each of his three sections, Schlosser exerts his own authoritative conclusion: "Left to its own devices, the free market always seeks a work force that is hungry, desperate, and cheap--a work force that is anything but free."

In the book's final section, "An Empire of the Obscene," Schlosser traces the trajectory of America's obscenity laws through the rise and fall of America's first pornographer king, Reuben Sturman. While ostensibly about pornography, "Empire" centers on the cat-and-mouse game between Sturman and the IRS investigator bent on bringing him down.

This classic face-off is so cinematic Martin Scorsese might have scripted it. However, the narrative is diluted by scattered anecdotes from porn-industry workers and Schlosser's vague conclusion. The content of our porn is the distillation of our desires, he explains, but we know that.

Throughout the book, Schlosser returns to the 18th-century philosopher Adam Smith, repeatedly tweaking his theories on free-market functions. In some instances Schlosser's observations are sharply drawn and borne out by lucid narrative. In a few, however, the author's valiant efforts to link his observations to his thesis are labored and exhausting.

Reefer Madness is at its best when Schlosser puts aside objectivity and, armed with facts and passion, speaks not only of the quantifiable harms of the shadow economy but on the ways in which black markets bankrupt our morality. Wealth of nations, indeed.

Reefer Madness

by Eric Schlosser (Houghton Mifflin, 288 pages, $23)

Eric Schlosser will read from

Reefer Madness

at the First Congregational Church, 1126 SW Park Ave., 228- 4651. 7:30 pm Tuesday, May 13. This event is and is sponsored by Powell's Books. Limited seating.