Bioshock Infinite: Burial At Sea DLC Set In Rapture

Irrational Games posted on their blog today that they would be releasing DLC titled "BioShock Infinite: Burial at Sea". The story brings Booker and Elizabeth back to the underwater city of Rapture from Bioshock 1. It takes place before the underwater cities' fall from grace.

I am very excited to see where Irrational Games takes the story. Why are Booker and Elizabeth in Rapture? What was the history with the little sisters? Watch the trailer and prepare to see two worlds merge.