Tigerlily's Orchids by Ruth Rendell (2011)

Dark dsychological suspense by the queen of the genre, Ruth Rendell.  Although a mystery, the murder doesn't take place until the middle of the book. The book is more about how we see ourselves vs how others see us.  And how we react to others can lead to unexpected consequences.  We peek into the life of each person, seeing them as who they really are; while also seeing how others perceive them.

Lichfield House has 6 flats plus a porter & his wife.  In one of the houses opposite, Duncan Yeardon, an elderly widower, watches the comings and goings of the inhabitants and invents his own version of their lives.  Stuart Font of flat 1 invitesw all of the neighbors to a housewarming party, bringing them together in ways that will change all of their lives.

Rendell is also the author of the Inspector Wexford series.