A few mysteries to recommend this month: “The Neighbor’s Secret,” by L. Alison Heller (Flatiron Books) The Neighbor’s Secret (Flatiron Books) Colorado author L. Alison Heller uses a book group as the setting for a complicated story of women and their secrets. At times, “The Neighbor’s Secret” almost reads like an interconnected collection of stories that come together in an Oh-My-God ending. On a whim, Annie invites the reclusive and very wealthy Lena to join her book group.