A dark and seductive demon haunts Trinity Heart's dreams, both waking and sleeping. While Logan, her first crush, is fighting battles with other Warrior Angels, Trinity develops a confusing friendship with Samuel, her Protector Angel. Trinity Heart thinks she and her twin brother are headed for a quiet summer vacation in London before their senior year of high school. But when she travels for a singing competition first to Paris, then to Stonehenge for the final concert, mysteries start to unravel and she finds herself in the middle of a war between angels and demons. A climactic scene at the mysterious Stonehenge ends in both triumph and tragedy for Trinity, and she learns a powerful secret that has been kept from her since her mother's childhood.