Seventeen year old Andi Creastwood is not your average girl, no, she is a guardian. guardians are groups of fallen warrior angels who have vowed to risk their lives to protect their assigned human. When Andi's protectee moves she gets assigned to a different girl who is in extreme danger, and gets really close to her brother. This unfortunate turn of events marks the first monumental change in the guardians long history and shows Andi's struggle with dealing with her emotions-her heart- for the first time.