`the halls of Rapture once again echo with sins of the past. Along the Atlantic coastline, a monster — somehow familiar, yet still quite different from anything ever seen — has been snatching little girls and bringing them back to the undersea city. It is a Big Sister, new denizens of Rapture who were once one of the forgotten little girls known as Little Sisters, known to inhabit the city's dank halls. No longer a pawn used to harvest ADAM, the dangerously powerful gene-altering lifeblood of Rapture, from the bodies of others and in turn run the risk of being harvested herself, the Big Sister is now the fastest and most powerful thing in Rapture. You, on the other hand are the very first Big Daddy, in fact the prototype, that for some reason has reactivated. You are similar to the Big Daddies familiar from the original BioShock, but also very different in that you possess free will and no memory of the events of the past ten years. The question is, as you travel through the decrepit and beautiful fallen city beneath the waves, hunting for answers and the solution to your own survival, are you really the hunter, or the hunted?