Invisible Prey (Lucas Davenport, #17)

In the richest neighborhood of Minneapolis, two elderly women lie murdered in their home, killed with a pipe, the rooms ransacked and only small items stolen. It's clearly a random break-in by someone looking for money to buy drugs. But as he looks more closely, Lucas Davenport with the Minnesota Bureau of Criminal Apprehension begins to wonder if the items are actually so small or the victims so random, and whether there might not be some invisible agenda at work here.

Gradually, a pattern begins to emerge — and it will lead Davenport to somewhere he never expected. Which is too bad, because the killers — and yes, there are more than one — are expecting him.