Home by the Sea. Power Moore Investigation Tales, #3

A decade ago, homeless people began disappearing from four neighboring towns. Day to day, the commuters making their way to and from work never took notice of the less fortunate they passed. They didn't notice as the number of homeless reduced. They didn't even notice when entire groups of homeless people vanished. A young woman, eager to find out where her grandfather disappeared to, began trying to find him.
When four police departments dismissed her, telling her that her grandfather would no doubt turn up when he wanted to, she was too young to realize she should pursue the matter further. Now, ten years on, she's stepped up and pushed harder for something to be done to find not only her grandfather but also the countless other people who seemed to have disappeared around the same time. Called in to investigate the disappearances, Special Agents Ashley Power and Tim Moore find themselves searching for - and finding - so much more than they thought they would.