Guardian's Keep (Unbound, 1)

Kol Hildr had spent the last century battling hellhounds and warlocks who sought to usurp his portal's magic. A mighty shape-shifter with the ability to change into wolf form, Kol made accessing the powerful gateway nearly impossible--unless you were a witch of Kelly Shane's talents. She had a score to settle and would do anything to close the portal that led to her unearthly prison. Though an alliance with her compromised Kol's very purpose, something about the little witch overwhelmed his fierce, battle-worn soul. But when he learned that Kelly's life might be in jeopardy, could Kol put aside the one thing he thought he valued most--the portal--to journey to the other side and save her?