In the aftermath of a Columbine-esque school shooting, Spenser is hired by the grandmother of one of the shooters who believes her grandson innocent.
With every new Spenser novel comes a spate of reviews proclaiming Parker's return to form. While I take these with a grain of salt, I did prefer School Days to the previous two Spenser books, Cold Service and Bad Business.
Susan Silverman is away at a conference for much of the book. Hawk does not appear, nor does anyone with a similar skill set (Vinnie Morris, Chollo, Tedy Sapp...), so Spenser must be self-reliant as in his first few adventures. Aside from his occasional remarks to Pearl the Wonder Dog, I found this refreshing. The plot held together better than recent efforts, too.
I wouldn't urge anyone not already a Parker fan to buy a book beyond Valediction (1984), but most of them are worth checking out of the library.