Final Fantasy XIII-2 is out in a matter of days, and before you jump into the time traveling adventure, here's a quick recap of Final Fantasy XIII. Read at your own discretion as there are spoilers hereafter.
Three years ago, Cocoon was almost annihilated. Saved by a band of outcast l'Cie, it now stands high above Gran Pulse, supported by a crystal pillar that rose at the sacrifice of Vanille and Fang, and serves as a reminder of the fearful lives the people once lived. It all started within the Pulse Vestige located near the seaside village of Bodhum. Hidden within its ruins was the fal'Cie Anima and once it was discovered, Sanctum quickly moved to Purge countless "tainted" citizens.
Serah Farron, who had been studying the local ruins and ventured inside, was branded a l'Cie by Anima. It wasn't until a number of days later when she returned to the Vestige that the Purge took place, with her sister Lightning and fiance Snow attempting a rescue. When they finally reunite, Serah turns to crystal, her focus complete, driving Lightning and her group to confront the fal'Cie, which in turn brands them as Pulse l'Cie as well.
Meanwhile, PSICOM launches an attack on the Vestige, sending the entire ruin plummeting down into Lake Bresha. Avoiding the clutches of PSICOM, Lightning, Sazh, Hope and Vanille make their escape onboard a PSICOM airship. Snow, however, remains behind with the crystalized Serah.
Unsure of their Focus, the group is split up as they pursue their own ends. Along the way, each of them come face to face with their own dark history. Eventually they are reunited and confront Sanctum's Primarch, Galenth Dysley, who reveals his true form: the fal'Cie behind this entire construction. The l'Cie then learn that their focus is to become the prophesied calamity Ragnorok and to destroy Orphan, the fal'Cie that powers Cocoon, contrary to what Serah told Lightning and Snow in the beginning.
In reality, Barthandelus and his fellow fal'Cie have constructed a grand scheme to destroy Cocoon, which will act as a catalyst to bring back The Maker, the creator of both fal'Cie and the mortal race. The l'Cie then make their way through a portal and down into Gran Pulse where they attempt to find a way to save Cocoon rather than destroy it. Their journey is cut short however, when Serah appears to tell them to transform into Ragnarok and destroy Cocoon. Rejecting her pleas, she abandons her disguise and reveals herself to be Barthandelus.
The l'Cie return to Cocoon to find its people in mass hysteria. They make their way to Edenhall where Barthandelus appears once again and attempts to drive the l'Cie into despair by destroying the crystals of Serah and Dajh, in the hope that it causes them to fulfill their destiny and destroy Orphan, and in turn Cocoon, summoning the return of The Maker. Upon Barthandelus' and Orphan's defeat, Cocoon begins its plummet towards Gran Pulse, but is stopped when Vanille and Fang combine their powers together to awaken Ragnarok's true form and summon a huge crystal pillar to hold Cocoon high above Gran Pulse.
On the surface below, Lightning, Snow and Serah are happily reunited while Sazh is overjoyed to see his son Dajh again. However, a darkness quickly surrounds Lightning and a crack in spacetime is opened, pulling her into the depths of the Historia Crux.
And so begins Final Fantasy XIII-2...