Data mining is the industry of the 21st century. Commercial companies collect information about us from thousands of sources - credit cards, loyalty programs, hidden radio tags in products, medical histories, employment and banking records, government filings, and many more - then analyze and sell the data to anyone willing to pay the going rate. Some people approve, citing economic benefits; others worry about the erosion of privacy.

But no one has been prepared for a new twist: A psychotic killer with access to the country's biggest data miner - Strategic Systems Datacorp - is using detailed information to work his way into the lives of victims, rape, rob and kill them and then blame unsuspecting innocents for the crimes. The killer's in-depth knowledge of the victims and his ability to plant damning evidence mean that even the most vocal protests of innocence go ignored by the police and juries.

The perpetrator has, in short, found a perfect means to literally get away with murder - until one of his fall guys turns out to be Lincoln Rhyme's cousin, Arthur, who is facing certain conviction for first-degree murder. Though the two Rhymes haven't had any contact for years, Lincoln agrees to look into the case. In the process he unravels a spider's web of crime that the killer, known only as Unknown Subject 522, has woven.

Rhyme, Amelia Sachs and the cast of the previous Rhyme books find themselves up against their most insidious villain yet, a man obsessed with collecting - from junk on the street to intimate details about our lives and the ultimate trophy: human lives themselves. Something he sees as mere streams of data. This is a man proficient with razors and guns, but whose most dangerous weapon is the information that he wields with ruthless precision against those he targets on a whim... and against those who try to stop him.

"How," Rhyme says, "can you defend yourself against the man who knows everything?" As the invisible 522 attacks his pursuers through identity theft and outright torture and murder, the struggling police have to turn to the likely source of the data the killer uses - the eerie and monolithic Strategic Systems Datacorp, headed by the legendary data mining pioneer, Andrew Sterling. His "mission" is the creation of a global empire based not on politics or money but on information. "Knowledge is power," Sterling continually reminds.

And for Lincoln Rhyme, the case has an added dimension. Arthur's re-emergence draws him back to his childhood and teen years and forces him to grapple with a tragedy from his past that he has avoided for decades.