This is book 2 in the Outlander series.
Since I think everyone should read this series, I don't want to accidentally drop any spoilers.
Suffice it to say that this book is awesome. It continues the story with Claire and Jaime in 1745 Scotland.
Claire is also in the twentieth century, 20 years after she returned and she has a grown daughter. She has brought her daughter to Scotland in order to tell her the fantastic tale of Claire's journeys.
Read these books.