Harbour Street by Ann Cleeves

This is a DI Vera Stanhope novel. 

A few days before Christmas Margaret Krukowski is stabbed and killed on the Metro.  Detective Joe Ashworth is in the same carriage as Margaret when she is stabbed.  The carriage is packed with people commuting home from work, Christmas shoppers and school children.  No-one saw Margaret being stabbed.  

As Vera and Joe start to investigate Margaret's murder they uncover interesting information about her past.  For many years Margaret had lived in the same Harbour Street house in the town of Mardle.  A lot of the residents of Mardle have been there, and known each other, for years.  They are very good at keeping each other's secrets.  

A few days later a second women is murdered.  She had also been on the same train as Margaret.  Vera and Joe need to find all the connections between the two women and track down the murderer.  

Some of Ann Cleeves' Vera Stanhope novels have been televised.  I have not seen any of these, but having now read one of her books and enjoyed the story, I will look out for the next series.