Books in the Powers That Be series

Two years have passed since Michael Pierce and Dan Renhoff returned to the Outer World. For Michael it has been two years of restlessness, grief, guilt, and increasing anger.Feeling abandoned by all except his closest friend, Michael conceives a plan to return to Inner Earth, vowing to "set things right." Uncertain of Michael's exact meaning but hoping his plan will lead to some badly needed closure, Dan accompanies him to what they believe will once again be the entrance to that magical land.But they find themselves confronted by a mysterious messenger, a being that speaks of a need they must promise to meet and a price they must pay. Will Michael and the Holy Presence be enough to meet this need? And, more importantly, what will be the price of their return?