The book begins with a family: father, mother, and two young daughters, Merry and LuLu. In a drunken rage, the father murders the mother, and stabs one of the daughters, Merry, before he is restrained by an adult that LuLu has screamed for. Merry survives, barely, but is deeply scarred - and the physical scars are just the beginning.
The two daughter's lives are always connected. They are literally all that each other has (their mother dies, and their father is sent to prison). They go to a relatives home, briefly, before being sent to an orphanage, and then taken in by an older couple with grown children. While Merry and LuLu are competely entangled in each others lives, and in many ways, completely dependent upon each other, they are also completely different: Merry continues to speak to her dad via letters to prison, and regular visits; LuLu chooses to ignore him, to rip up his letters and never visit, despite his begging.
Since it's a fiction book, I'm going to stop there, before I give anything away. Let me just say that I loved it. I cannot recommend it strongly enough. (Though, I will say that I struggled through the first 50-100 pages. It drags a little in the beginning, but then it picks up, and I was so glad that I stuck through it).