Minerva's Den offers a brand-new, self-contained BioShock story, presenting a side of Rapture you've never seen before. Seek out the tools you'll need to unlock new goals and spaces in the order you choose. Face Rapture's full range of opposition as you increase in power---a new challenge is always right around the corner. Expand your combat abilities with the experimental Ion Laser and chaotic Gravity Well Plasmid, unique to Minerva's Den. Face off against the new Lancer Big Daddy, the most advanced Protector that Rapture ever produced. Explore every shadowy corner of Minerva's Den, unraveling the mysterious past of The Thinker's inventor, and the dark secrets hidden within the unfeeling, omniscient machine he created.

(Xbox.com)