Legacy of the Immortal Guardians explores Seraphina's and her friends' entwined fates as they walk the precarious line between the mortal and immortal worlds. Finn, Lila, and Rowan are among them. The group is put in charge of stopping a renegade force and discovers that they are in a dangerous old American mansion. When the group comes across a scared girl who has been captured by a mysterious entity, they use their special skills to defeat the enemy. They are reminded that their mission to preserve cosmic balance is never-ending as they solve the mysteries surrounding the girl's connection to their ancient lineage, with dawn ushering in a new era in their enduring legacy.