Aer Soroval and the Wildwind twins are sent by King Dalyn to investigate the crater called Phantom Deep. Within it, they find the Tartarus Gate, a spherical prison which defies logic as its inside is larger than its outside. They also fight a strange creature which spontaneously appears and defeats them. As a result, Aer obtains a new set of swords she dubs Gravity Blades which seemingly allow her to jump higher and descend slowly. They also seem to guide her on her journey.
Aer later decides to return to Phantom Deep in hopes of conversing with the strange creature.