Jack, the sole survivor of a plane crash in the middle of the Atlantic Ocean, discovers the entrance to the recluse underwater city of Rapture, at the end of a civil war which left most of it in disrepair. Finding himself trapped in a strange and dangerous dystopia, and with only a mysterious man called Atlas helping him, Jack has no choice but to fight for his survival against Rapture's mutated and monstrous denizens, as he tries to find his way back to the surface.