An ex-police officer agrees to help a young woman who believes her mothers death was no accident. The investigation makes him feel alive again and he doggedly follows leads until he unearths a nurse coming to the mother’s apartment to help her daily. 
But she may not be who she appears to be (suspense…). The subheading of the book ‘even angels have their demons’. 
The story is well told from several perspectives. The pace moves fast, with the main part of the story set in Paris and then moving to Venice. 
I liked that the whole story fitted together like a well-made jigsaw puzzle. It’s one of the books were all the clues are laid out for us (when we think about it post-finishing…sigh). Very satisfying and all the random clues and loose ends well tied off.
I will be reading more of this author who writes with a familiarity about Paris and its suburbs. 

I read it in English (you might have noticed the photo of the book is in French - no, I am not that good...) 

Other Guillaume Musso books (English and French language) 
The secret life of writers
The reunion 
The stranger in the Seine
Where would I be without you
Will you be there?