Harbringer's Cave is a fictional location in The Book Of Harbringer. The exact location is a secret of Harbringer's family, thus, after Harbringer's father's death, Harbringer and those he trusts are the only ones who know its location. The cave is in Morrowgrand's western mountains. Deep within the cave, there is a magical link to outside the kingdom which leads to a forest not far from Borshadow's medicine farm.
Upon Harbringer's return to Morrowgrand, he uses to cave for him and those he trusts to hide and work in secret.