So Pure a Heart (Daughters of His Kingdom #4)
Amber Lynn Perry

Leaving his young ward to join the fight for liberty is the hardest thing Joseph Wythe has ever done. Nearly. The most difficult happened ten years past, which he tries his best forget it. Seeing Hannah Young again after all this time does something frightening and wonderful to his soul. Though her determination to spy for the Patriots is honorable and brave, he will never allow her to take such a risk without him to protect her, no matter how she protests—and no matter how he knows he will ache all the more for the thing he always wanted and still could never have.