Sinner (The Wolves of Mercy Falls #3.5) by Maggie Stiefvater

You thought it ended with FOREVER, but there's another story to tell - the one of Cole and Isabel, pivotal characters from the Shiver trilogy. Cole and Isabel share a past that never seemed to have a future. They have the power to love each other and the power to tear each other apart. The only thing for certain is that they cannot let go. Format Paperback 400 pages | Publisher Scholastic | Language English | ISBN13 9781407145730