One of his friends is Robert Arctor. Bob also has a problem. He needs to connect with a high-level dealer of Substance D, the illegal narcotic also known as death. He's trying to move up the dealer chain through his girlfriend, Donna, who won't put out, but whom he still digs. But none of these issues are his problem. His problem is that he's using death, which wrecks your mind before it takes your life.

Fred, too, has a problem. He's an undercover narcotics agent in the Orange County Sheriff's Department. In his scramble suit, which hides him within a million and a half shifting images of men, women and children, he is unrecognizable. That's why his boss assigns him to surveil Bob Arctor—Fred's undercover persona—as a possible Substance D dealer. But that isn't Fred's problem. Fred's problem is that he no longer realizes he and Bob Arctor are the same person.

There's an even bigger problem, which endangers everyone. More than one government organization is fighting Substance D, and they are using one another, hiding from one another, possibly even working against one another. But that's not the problem. The problem is that the law enforcement organizations may be opposing a more powerful drug supplier than they can imagine. ...

A mind-altering experience

Philip K. Dick (1928-1982) is one of the 20th century's most important SF writers. His large and influential body of work includes "We Can Remember It for You Wholesale" (1966), which inspired the Arnold Schwarzenegger movie Total Recall (1990); Do Androids Dream of Electric Sheep (1968), the basis of the Ridley Scott movie Blade Runner (1992); Flow My Tears, the Policeman Said (1974), which received the John W. Campbell Memorial Award; and Hugo Award winner The Man in the High Castle (1962), his best-known novel and one of the finest alternate histories ever written.

In the 21st century, PKD may become the field's best-known writer. One reason is his popularity in Hollywood, which regularly turns his stories and novels (most recently, A Scanner Darkly) into movies. The other reason (which causes the first) is his themes, which are increasingly relevant to our world of virtual reality, genetic engineering, digital replication and growing government intrusion into our private lives. These themes include the uncertainty of identity, the indeterminacy of reality, the difficulty of distinguishing the imitation from the actual and distrust of governments.

These themes are central to A Scanner Darkly. Every character who uses Substance D loses contact with reality, entertaining druggy fantasies before becoming hopelessly lost in delusion. The narcotics agent Fred becomes so disconnected from reality that he thinks his undercover identity, Bob Arctor, is a separate person. Meanwhile, almost no one (including Fred's sober boss in law enforcement) notices that Bob Arctor is an artificial construct. And the secret source of Substance D is very highly placed (and not much of a surprise to readers familiar with the 1980s connection between cocaine and the CIA, though it must have shocked some readers in 1977).

By exploring its themes through the medium of mind-altering substances, A Scanner Darkly takes an unsettling yet sympathetic journey through the mindscapes of the drug addict, from the anxiety about running out to the paranoia triggered by the sight of a cop, and from the inane conversation (so scintillating when stoned, so stupid when straight) of the marijuana smoker to the persistent delusion of the hopelessly brain-damaged. As a result, the novel isn't very plot-heavy, and the final section gets pretty disjointed as Fred/Bob Arctor's mind disintegrates. This is not the book for plot-oriented readers, or for those who like tidy endings. But for anyone seeking insight into the drug-addicted mind or the nature of reality and identity, A Scanner Darkly is required reading.