IN LOS ANGELES a twenty-something fashion photographer goes to the Room, a back-alley bar with no sign over its entrance. Around midnight a man walks in and hands the photographer a packet of heroin in exchange for a hundred dollars. The photographer disappears into the men's room and emerges a few minutes later, grinning and obviously high.

In a central city neighborhood of Chicago the latest cheap high for teenagers is a blunt, also known as a marijuana cigar. To make a blunt, the teens open a cigar and mix the tobacco with marijuana. If they can get their hands on other drugs, they mix them in, too. Sometimes they dip the cigar in malt liquor, creating what is called a B-40.

In New York City a top Wall Street economist takes a four-week medical leave of absence from his firm to enter a drug rehabilitation program. He...