Booker DeWitt used to work as a Pinkerton agent, but his methods were a little too rough, and his gambling debts have forced him to take a new job. His mission? To travel to the floating city of Columbia, a place created as a monument to the successful American experiment with Jeffersonian ideals, and rescue a young woman named Elizabeth. She has been trapped in a tower since she was five years old, and as Booker finds out, she has a powerful protector with everything invested in keeping her there.

This is the world of Bioshock Infinite, a game that was demoed for the press at a pre-E3 event in Los Angeles by Ken Levine, the game's creative director and cofounder of Irrational Games. It's not just that the game looked good—it looked amazing—it's the subtext and commentary the game provides under its exterior that drive the game just as much as the weapons and setting.

Help me make the most of freedom and pleasure (nothing ever lasts forever)

In the beginning of the demo Dewitt begins looking around a gift shop, filled with fireworks, masks of Abraham Lincoln, and American flags, as Elizabeth plays with all the toys and items. She's childlike, almost whimsical, and it's your job to keep her safe until you can get her to the leader of the city. Once there, she hopes for some answers about the terrible power she is only now learning to control.

Elizabeth can do very interesting things with her mind. In one scene she tries to heal a dying horse, and the power gets away from her, bringing the two of you to what appears to be the recent past. Tears for Fears plays in the background, and you glimpse a movie theater playing "Revenge of the Jedi." That title was deliberately chosen, and is a sly way to note that she's not only ripping holes through "normal" time, but also through parallel timelines. The game will feature combat where she opens these rifts to move objects around the world, or to grab useful items from other versions of our past, and maybe the future.

The combat is thrilling, with Booker zipping around the world using skylines and the tracks of the elevated trains. You hang underneath them and zoom from area to area, dodging the enemy and fighting your way through the streets. Levine told us that Elizabeth will be able to take care of herself when you're off doing a side mission or finishing an objective, and if you peer down while zipping along the skyline at one point, you see her kicking an enemy in the crotch. Even without her powers, she's a capable character, although very innocent.

Throughout all this, you're being hunted by Elizabeth's protector and keeper, the Songbird. He is a huge, menacing, mechanical bird that patrols the streets looking for her, trying to take her back to her tower. "You will not let him take me back," she pleads, placing your hands over her throat. Although both DeWitt and Elizabeth are fascinating characters in their own right, the relationship between Elizabeth and the Songbird is what grabbed me while I watched the demo.

He hit me (and it felt like a kiss)

I asked Ken Levine why these characters were so interesting to him. This is the second game he's helped to create where an innocent character is protected by something monstrous.

"They're not just protectors, the Big Daddies... a [Little Sister] was an economic engine. So his job was not just to protect her, but to make sure that economic engine continued," Levine said. "It's not clear what the Songbird's job is, it's clear that their relationship is complex. He obviously has feelings for her... "

It's a fascinating answer, and it hints at the reasons Elizabeth has been kept away from the world for so long. What is she doing that's so important to both sides fighting for control of the floating city? If she's using her ability to transport people and objects across space and time, why does she barely know how to use these powers when we meet her in the game?

During one of the final scenes in the demo, you're pinned down by the screeching, rampaging Songbird, and Elizabeth throws herself between you and her "protector," begging him not to kill you. "I'm sorry I left!" she cries, "Take me back home!" His demeanor changes instantly, and he almost nuzzles her with his metal beak.

"I once dated a girl who had an abusive ex-boyfriend, and I saw conversations like that, with bargaining, and being very defensive of that guy. She was very defensive of that guy, and it always struck me," Levine said. "I think people have very complex relationships, and people and giant, thirty-foot tall birdlike creatures can have complex relationships."

The problem is that as much as Elizabeth wants her freedom, she also seems mentally shackled to the Songbird, and she appears to understand how much he cares for her. "He's all she knew, and he's conditioned to feel things for her and to be very jealous... of her leaving. He's not just doing a job—he's obviously engaged." Levine explained.

At the end of the demo the Songbird flies off triumphantly, Elizabeth held in one giant talon, her screaming face pleading for you to do something. DeWitt jumps off the window after her, falling through the air, and the scene fades to black. It's clear that this isn't just a job for DeWitt anymore. There was no hesitation in his movements, just pure resolve: he's ready to give his life for Elizabeth, a young woman who seems to be broken by her relationship with her only... friend? And that friend is a giant metal bird who will kill anyone who gets between him and the woman he cares for.

"So why? I don't know what fucked up part of my life makes me do this stuff," Levine said, laughing. "I don't know. Some fucked up part of my life."

Bioshock Infinite is coming to the PlayStation 3, Xbox 360, and PC in 2012.