Amazon description
Ruth smiles, but beneath the surface nurses a hatred as powerful as the sea, and as sharp as the coldest of blades. The object of Ruth's malevolence is her cousin, Elizabeth - orphaned at nine months and raised by Ruth's parents as their own - whose very presence stole Ruth's birthright as only child. From this twisted sense of betrayal grows an envy, dark as night, from which there can be but one refuge: Elizabeth's destruction.