This hit all my buttons for a mystery.
I despise mysteries that rely on coincidence for a solution—all the clues should be available in the text, and a careful reader should reach the same conclusion as the protagonist. If the author is really good, even a brilliant reader won't get there too soon.
Which is not to say coincidence can't have a part—the odds just aren't that good that anybody, even a big city cop, could stumble into these scenarios. So, A Tap on the Window does begin with a coincidence: Cal Weaver just happens to be in front of Patchett's bar when a young girl is hitchhiking in the rain, and she knew his son. But that's where the coincidence ends; the rest is tightly plotted detective work.
Throughout the story there are anonymous interludes letting us know about the crime that's being covered up, but we're carefully kept in the dark about who the perpetrators are, and there are multiple candidates. I worked it out, but not so soon that it would ruin the story for me. If it's too easy, it just gets boring.
There's just one thing that jarred: "He looks like a child who’s been promised a trip to Santa’s Village." Really, Barclay? Do you think the kids of Griffon, NY, dream of a trip to Santa's Village? I'm not sure anybody does any more, but it's a Southern Ontario thing, probably best remembered by those of Barclay's and my age.