The Girl on the Train by Paula Hawkins

Every day Rachel takes the commuter train out of London.  She looks out the window at a small town where she lived before her divorce and fantasizes about a couple she can see from the window.  So young; so happy; so affectionate.  Then one day she is surprised to see the young woman passionately embracing another man.  Her fantasy is destroyed but the greater shock comes when she reads in the news that the woman has disappeared.  Rachel believes what she has seen from the window is the key to solving the mystery of the woman's disappearance. Complicating her thinking is the fact that on the day the woman disappeared, Rachel found herself in the same town bloodied and bruised with no idea what happened - one of her many alcohol induced black outs.  But Rachel is just one of the narrators.  Megan, the woman who is missing and Anna, Rachel's husband's new wife also have stories to tell.  Although it is difficult to be sympathetic to any of these damaged women, they are not the nastiest characters in the book.  Three narrators provide three perspectives on a single murder but that may not be the only murder.  Very Gone Girl -ish.