I'm not overly familiar with Ruth Rendell's work, and stumbled across this by chance in the local library. I think it's a fascinating read, exceptionally well-written and shot through with wonderful descriptions of an unnamed city (somewhere in the UK, probably in England) through the changing weather and seasons between winter and the end of summer.
Overall, it combines a fairly standard "husband dumped for former lover" with an initially standard "unexplained murder from years ago" with an original "schoolboys playing at spies". Along with these three major plot lines, other strands intertwine. Although the coincidences that link the strands are possibly a little *too* coincidental, there are some satisfyingly surprising reveals, some unexpected twists and turns, and a well-crafted murky ending.
The writing is quite dark, and the tone quite subdued and restrained. I found it very intelligently written, by which I mean that not everything is explained and much lies waiting to be deduced by the thoughtful reader. There's much less dialogue than in many novels of and about the period, and the author manages to write many passages of descriptive prose that deserve careful, loving reading. Especially the description of the city, as mentioned earlier.
An excellent book.