set-up has potential, not realized

Widowed film buff history teacher is on exchange at a nearby public school ("private" to Yanks); his younger girlfriend DS is coincidentally assigned there also when teachers start dropping dead. The situation has potential, but nether the characterization nor the performance is as good as should be. Teacher upstages his gf in policing; lots of stereotyping about public schools and generational conflicts among faculty; past the main pair and a memorable chair of trustees, characters are hard to tell apart. Reader's voice is good, but he (apparently) doesn't pause when there is a break in the typeface (you know, when sometimes there's not a chapter break but just extra white space); SO the scene changes, with no warning, and different characters are in a different place talking about different topics. It is RARE that I don't finish a book, but I might return this -- about 75% thru now, and I'm just not hooked.