At the age of 17, the poet Shelley fell in love with his cousin, Harriet Grove. She returned his affection, and for a time the youthful romance flourished. Drawing on Harriet's diaries for 1809-10, on letters and journals written at the time by Shelley and on the accounts of their family and friends, this book examines the development of their love affair, its abrupt ending, and the influence which his passion for Harriet had on Shelley's early work.