Twilight Sparkle has learned a new trick; a spell that allows her and her friends to enter realistic dream worlds within the margin of their subconscious. But these dreams are as malleable as they are dangerous, and each additional trip they take into the mind to study this new magic threatens to cause them serious harm and skew Twilight's perception of reality.
Meanwhile, Spike is beginning to struggle with an old demon of his again. Only this time, his greed is more tempting, more malicious, and sentient: scheming to consume his every thought like a virus until there is nothing left of him but avarice.
In danger of watching their friend become their new nemesis, Twilight, Rarity, Pinkie Pie, Rainbow Dash, Applejack, and Fluttershy must travel deep into Spike's subconscious and plant a thought in his mind that will forever make him contradict his dragon heart's innate inclination for greed. However, their mission will not be easy, their journey will not be safe, nor may their intentions even be justifiable in the face of their actions.
But sometimes, to save your friends, you must change them.