Bioshock Infinite Walkthrough Part 15: Bring Us the Girl (Library to Battleship Bay)
Start and keep running down the stairs and along the walkways. You will see something tear 2 massive holes into the side of the monument. Just keep running. The frequent shaking seems to make it hard for Booker to stay running so expect to repeatedly have to start running.
When they get to the elevator you will be introduced, in a sense, to the Songbird. The elevator will come down on its head shortly after it tries to get through. Once that has happened drop down into the wreckage Just ride the sky-line after that until it collapses. The Songbird will continue to chase you even as you fall but it seems to be warded off by the water as the pressure seems to crack one its protective eye coverings. This leads to another grey scene where the voice and talk of the debt.
When Booker finally comes to for a second time head up the beach. There is a Voxophone sitting under the Northing Changing Cart. This one is Ed Gains: “Born In The River”. Be sure to take some time to search the various baskets and talk with the people learn if they have seen a girl. No one seems to help him. Just head into the arcade after that.
Once inside the arcade, go around the first wall and look to the right. This leads to the Kinetoscope: “Battleship Bay”. After that head out onto the second beach. Take a little time to search the beach to replenish Booker's health. After that head down the pier to where you see the people dancing. Elizabeth is having a great time just dancing. Booker will work to get her attention. Interact with her to finally succeed. DeWitt will tell Elizabeth that the First Lady Airship is headed for Paris. Apparently he is under orders to tell her whatever she wants to hear to get her to New York. Elizabeth will run up the beach and through the turnstile in the back, leading to the upper Boardwalk. Take a little time to search the few barrels you can on the way.
When you make it to the entrance of the Upper Boardwalk a Familiar, Eerie Couple will greet you there. There are offering Elizabeth 1 of 2 cameos to put on her choker. You can choose either a bird or a cage. This is strictly a superficial choice so choose whichever you like more. There is a little griping by one of the couple about your choice but it should be expected by now. Just after that little scene the clouds will move away from the Angel Columbia statue on Monument Island, revealing its destroyed form. The people around you and Elizabeth do not take too well to it. Booker and Elizabeth both just want to get out of there. Head forward toward the security checkpoint.
Both Elizabeth and Booker do not want to go through security. The solution is over to the right of the checkpoint. After the drunkard, Pete, is done talking with the Police head all the way over to the and to the door with the flashing lock in the center of it. Interact with it and after Booker tries the door then Elizabeth will go and pick the lock very quickly. From this point on try to find Lockpicks wherever you can. This will let Elizabeth open doors to optional areas. The doors can take 1, 3 or 5 lockpicks so try to keep a minimum of 5 on hand. Take some time to search the office the two pass through after getting through the door to find supplies, Salts and Health. From there just head on up the stairs and over to the Dollar Bill Vending Machine. Buy what you want then continue down this hallway, not the one to the left with the washrooms, to the double doors. Go into this storage room and look on the table to find another piece of gear. After that look to the right, in the wash basin, to find a Voxophone: Daisy Fitzroy: “Heaven”.