Apples of the Queen

An enormous tree - higher than a mountain - emerges one day in the middle of the city. Despite the damage, the citizens consider the tree a blessing. "Queen's apples" grow from its limbs. All who eat are cured of illness and disease. Humanity rejoices until it is discovered that the apples cause some people to transform into murderous monsters. However, others are not only immune to this transformation but receive extraordinary powers they can use to fight off the creatures. Are the transformed people doomed to die or can they somehow be saved?