Strange Flowers by Donal Ryan

In 1973, 20-year-old Moll Gladney takes a morning bus from her rural home and disappears. Bewildered and distraught, Paddy and Kit must confront an unbearable prospect: that they will never see their daughter again. Five years later, Moll returns. What – and who – she brings with her will change the course of her family’s life forever.