Grace Livingston Hill 
The Seventh Hour [EPUB ebook] 

Dana Barron was only a small boy when his mother took her newborn daughter, Coralie—and left. Despite their hurt and grief, Dana and his father built a happy life together, one filled with love, faith, and contentment. Then Dana’s father died, leaving his much-loved son with one final request: Be reunited with your mother and sister.
Aided by his friend, Bruce Carbury, Dana enters his mother’s world: the turbulent world of New York society. Suddenly he finds himself caught in a struggle to overcome twenty-one years of separation and to fight against deceit, bitterness… and murder! Will Dana and Bruce get through to Coralie, Dana’s beautiful, troubled sister? Will Dana’s faith be strong enough to lead him—and Coralie—to safety?