After a lot of tragic events, Kion and his Lion Guard finally arrive at the Tree of Life. They are surprised to find that a mysterious group of lions who live there won't allow him in. As he grows desperate to find new healing, his friendships with the Lion Guard break apart even more. As the same time, a growing darkness finds its way inside his heart. Beginning to hold more grudges, being more hostile, and just not having the will to keep fighting, Kion slowly turns into a lion his friends have never seen before. Will they find a way to prevail, or is this the end of Kion's story?