Chasing Sunsets, Angels Walking Series by Karen Kingsbury and published by Simon & Schuster.
Mary Catherine grew up in a comfortable life, despite an array of health issues including a congenital heart condition (which she quietly obsesses over). She loves her parents, who are quite wealthy, but the lifestyle never appealed to her. Instead, she pursues meaning through an abundance of charity work, always giving away a part of herself in service of others.
After her project with a local youth centre comes to an end, Mary Catherine decides to travel to Uganda on a mission to meet the two children she sponsors - and to find out if her donations are actually helping. Accompanied by Tyler, Sami, and Marcus Dillinger, Mary Catherine arrives in Africa only to find a makeshift orphanage with seventeen children and no one to care for them.
They return home with heavy hearts, and Mary Catherine knows there is more work to be done. Intent on returning to Africa, Mary Catherine quits her job and leaves a budding romance behind to fulfil her desire to help others. Inspirational and moving, Chasing Sunsets is the story of one woman's deep longings of the soul, and the sacrifices she's willing to make in search of healing.