Bioshock Infinite Walkthrough Part 58: Flight Of The Songbird (The Operating Theater)
Head on through the doorway and around the bends. You will find the Lutece Twins appear just behind one of the Tears. They explain more of what is going on, explaining this not a “What” situation, but a “When” situation. Head on up the slope toward the one open door. You will find someone there, Elizabeth, who has been drawing you in for a while. Things that have been set in motion are coming to their final step. Take her hand and see what comes of it: DeWitt is someone willing to take this gamble. This Elizabeth explains what happened to her to the backdrop of New York's destruction. She gives Booker a card, something encrypted that only Elizabeth can understand. She will then send Booker through another Tear, back to another time?
You appear in a hallway. Head on down the stairs and go through the double doors. Booker will find himself in the surgery, just as Elizabeth is getting connected to the Siphon. Booker can now work to stop what is about to happen, what happened to Elizabeth. Run over to the right and follow the cable as it leads up the stairs down the short hallway.
As Booker reaches the bottom of the stairs, equip Possession and throw one at the Gun Automaton sitting at the top of stairs. There are a number of Beast Founders to deal with but the Automaton on your side plus a favorite weapon will tear through them quickly.
At the top of the stairs head over to the left. In this room you have 2 Gun Automatons to deal with. Once again, hit one with possession. It will go a long way to keep things in your favor. It will be fairly damaged by the other Automaton and the Beast there. Now head over to the left and look for the trail of cables again. It will lead through a few turns but it leads right to the first of the 2 generators. Pull the lever in this control box to shut down the Generator.
Head back on through to the room where the Automatons where. You will encounter a Motorized Patriot (A Comstock Version too). Possess it to get some free aid for a few seconds and some free shots on its vulnerable gears. There are still at least 5 Beasts to deal with so make good use of Return to Sender here.
When the Beasts and Patriot are down go through the other door, where the Patriot came from. Head on up the stairs to the second generator switch. Throw it to bring the surgery to an end. Now head on down the stairs and over to Elizabeth. Go over to her right-hand side to free her and help her with her corset. After that head on up the stairs to the area with the generators. Go to the locked door between the 2 Generator Rooms. It takes 3 Picks but Elizabeth can get it open. Head in and up the stairs to the desk. Search it for some loot then grab the Voxophone (Dr. Harrison Powell “Pavlov's Bell”) and the Infusion next to it. Now head for the opposite gate and ask Elizabeth to open it up. Head on through to the elevator beyond it to get into the Library.