I bought this when it was first out in paper in the UK, and liked it well enough to keep. Last week I was scanning the shelves for something put-down-able to reading while grading midterms, and pulled _Every Breath You Take_ off the shelf. Wow, did I make a mistake.
Not only could I _not_ put down the stalker plot, even the second time around, but the characters are so well crafted that they grip the attention as firmly as if they are in the room with you. Every woman wants a friendship like the one Laura and Helen have built, a refuge as real as the cottage they share, but as open to other people as is the hearth they share with a wonderful variety of secondary characters.
Laura's work and love partner, Sonny, is an almost too-good-to-be-true sensitive new age guy, but the author keeps his page-time to a minimum, thus preserving his credibility. The people whom Laura meets in the course of the investigation are all wonderfully varied -- quirky or steady or fragile or pompous. Angel, a character who has a key minor role, is exquisitely drawn and given a depth and complexity of feeling that never topples into stereotype or bathos.
Spring does places particularly well. Her London, Cambridge, Norfolk settings all ring true in different ways, all open windows with real views, sights, sounds, smells and atmosphere that the reader can move into. Her insights into college departmental politics are also wickedly realistic.
And yes, it is frightening. It's a hard balance to get a capable woman to feel at risk, but with Laura Principal, Spring manages to make the danger real without making the woman either a cowering victim or a risk-taking idiot. The plot is brisk, believable, and packed with enough twists to keep a reader from feeling comfortable. You can see the end coming before either Laura or the police get there, but that simply increases the tension for the reader.
Buy it and keep it to read again!