Hush Now Baby (Sloane Monroe Series) (Volume 6)

From New York Times and USA Today bestselling author Cheryl Bradshaw: 

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On a crisp, fall night, Serena Westwood wakes to the faint stirs of her crying baby. Bottle in hand, she tiptoes to the other side of the house, sneaks up to the crib, looks in. A wave of panic grips her as her real nightmare begins. Inside the crib, there is no baby.