From Amazon:

Jemima, who is raising the child her late twin sister left in her care, is approached by Italian billionaire Luciano Vitale and treated with contempt. He demands to know where his eight-month-old child is, naming Jemima’s sister as the surrogate who gave birth to the baby and stole him. Jemima fears Luciano will take her nephew away if he discovers that she isn’t her sister. So Jemima pretends to be her sister and travels with him to his mansion. She must somehow maintain her secret or risk losing her adopted son forever.