The "Crossfire Series" is a popular collection of contemporary romance novels written by author Sylvia Day. The series follows the intense and passionate relationship between the main characters, Eva Tramell and Gideon Cross, as they navigate their emotional struggles and personal traumas. Set in New York City, the series explores themes of love, desire, and healing. It consists of five main books, starting with "Bared to You," and has garnered a large fanbase for its steamy scenes and complex character development. The series has also been compared to E.L. James's "Fifty Shades of Grey."