Goal: Locate the Train Station
Make your way through the Cohen's Collections corridor and to Dionysus Park. You will face a Houdini Splicer here. Houdini Splicers throw fire and can cloak themselves momentarily. As with any other Splicers, these guys are vulnerable to Anti-Personnel Rounds. The Cyclone Trap Plasmid also works quite well, because you can set one under a Houdini Splicer from afar and then move in and fill them with lead when they hit the ground.
When the Houdini Splicer is dead, exit via the doorway at the east end of the area. Look for an Audio Diary (Patronage) on the shelf next to the puddle of water straight across from the doorway.
With that, proceed up the stairs and through the doorway. Move straight through the falling water and down the stairs there to find another Audio Diary (A Gift from Billy). This diary contains the code to open the locked door in the previous area. There is a Power to the People weapon upgrade station and another Audio Diary (Lamb's Time is Over) behind this door. Backtrack to the area where you faced the first Houdini Splicer and input the code 1080. The door is next to the Vending Machine at the east end of the Cohen's Collection corridor.
Input 1080 into the Keypad to open the way to a Power to the People station and Audio Diary.
After collecting the diary and using the weapon upgrade station, make your way back to where you found Billy's diary. Proceed through the automatic double-door next to the falling water. Hack the Security Camera in the next room and continue up the stairs. Look for some Trap Spear Ammo in the Ammo Vending Machine at the top of the stairs and then kill the Leadhead Splicers in the next room. Proceed through the doorway and turn left to spot an Audio Diary (Lamb's Idea of Art) on the base of the statue there.
Once you have the diary, exit through the automatic double-door at the other end of the room. There is another Audio Diary (Lost and Found) at the centre of the carousel here.
Goal: Meet Stanley in the Train Station
Proceed through the Securis door at the east end of the room after collecting the audio diary to enter the Maintenance Access area. Kill the three Leadhead Splicers beyond the Vita-Chamber and then continue into the next area. Collect the Solid Slugs and Shotgun at the other end of this corridor. Kill the two Leadhead Splicers in the next room. There is another Power to the People station here; use it to upgrade one of your weapons, and then continue through the adjacent door.
Eleanor's next gift to you is a Launcher.
Through this corridor and in the next room is another gift from Eleanor: A Launcher, a First Aid Kit, and some ammo. Equip the Launcher and approach the door at the south end of the room. Fire a Frag Grenade at the two Splicers working the Turret to kill them. Through the door, walk across the station to the cabin window to speak to Stanley Poole.
Goal: Rescue or Harvest Three Little Sisters (Triton Theater)
Exit through the automatic door at the east end of the station after speaking to Stanley. Up the stairs and through the second automatic door, look for an Audio Diary (Lamb Flouts the System) next to the overturned trashcan behind the statue at the centre of the area.
One of the three Little Sisters is in the Triton Theater, accessible via the corridor at the south end of the Gallery Entrance, the area you are currently. Past the falling water and up the steps to your right is a Missile Turret. Hit it with a Hack Dart and make it friendly before entering the theatre.
Enter the Lounge through the doorway at the west end of the lobby. Kill the two dancing Houdini Splicers, and then approach the locked door at the bottom of the steps at the north end of the lobby. Hack the Door Control panel to open the door. Pick up the Audio Diary (Learning Poker) on the Filing Cabinet in the corner straight across from the door. Return to the theatre lobby once you have the diary.
Hit the sparking Door Control lever in the Triton Theater lobby to uncover some Proximity Mines for your Launcher.
Back in the lobby, hit the sparking Door Control lever with an Electro Bolt to open the gate. Collect the Proximity Mines for your Launcher here and then continue into the theatre to face the Big Daddy.
The Little Sisters in this level are guarded by Elite Bouncers, a stronger variant of the Bouncer you faced in a previous level. You can make short-work of an Elite Bouncer with Proximity Mines. Sticking Proximity Mines to an object and then propelling that object with Telekinesis deals massive damage.
Start by finding a Splicer corpse. Use Telekinesis to pick it up. Press the X/Square button to place the corpse down somewhere away from the Big Daddy, equip your Launcher, switch to Proximity Mines and stick three onto the corpse. Propel the corpse at the Elite Bouncer using Telekinesis -- this should just about kill him. Switch to your Drill and hit him with Drill Dash, then just keep drilling until he falls.
Killing the Elite Bouncer in Triton Theater
When the Big Daddy is dead, Adopt the Little Sister or Harvest her on the spot. There is a gather spot in front of the stage, and another up in the booths. Again, ADAM gathering is completely optional.
When you're ready, proceed through the automatic double-door to the left of the stage. Look for an Audio Diary (The Secular Saint) on a bottom shelf in the far corner of this room.
After collecting the diary, head back to the corridor just outside the theatre and head up the stairs at the west end. Collect the Audio Diary (A Spy) on the railing of the booth here. There is another Audio Diary (Growing Up) in the hall leading to the Projection Booth, which is accessible through the automatic double-door at the east end of the corridor just outside the theatre. There is a Security Camera at the top of the stairs, so destroy or hack it before entering the hall. Look for the diary in front of the collapsed section of wall partway down. Continue to the end of the hallway and collect the Extended Reel Gene Tonic in the Projection Booth.
Look for the Extended Reel Tonic in the Projection Booth.
Goal: Rescue or Harvest Three Little Sisters (J. Fischer Gallery)
Leave Triton Theater and return to the Gallery Entrance. Kill the Splicers here, and then proceed through the automatic double-door at the west end of the area. Collect the Audio Diary (The Voice of the Self) on the piano in the next room. Exit the Piano Bar via the southwest doorway. Kill the three Leadhead Splicers in this room, and then use Incinerate to melt the ice mound covering the door to Imago Fine Arts.
There is Security everywhere in the Imago Gallery. Hack as many of the Security Cameras and Turrets as you can. A bunch of Splicers will eventually show up, and there is a Little Sister gather spot here, so they having some friendly machines here will come in handy
There is an Audio Diary (Falling into Place) embedded in an ice mound next to the doorway across from the Vent at the southwest end of Imago Gallery. Use Incinerate to melt the ice mound so you can collect the diary. Continue through the double-door next to the Vent to find the Hardy Machines Gene Tonic.
Use Incinerate to melt the ice mounds in Imago Fine Arts.
The Little Sister is in the J. Fischer Gallery, which is accessible via the double-door at the north end of the Promenade. If you've been following along this walkthrough, you know the quick way to kill a Big Daddy using Proximity Mines and Telekinesis. There is an Ammo Vending Machine right across from the door into this area; hack it, and then purchase at least three Proximity Mines. Hack or destroy the Security Camera in the southeast corner before getting started.
You first must find a corpse to attach the Proximity Mines to. Kill the Houdini Splicer here and pick up his corpse with Telekinesis. Move away from the Elite Bouncer and drop the corpse by pressing the X/Square button. Then, equip your Launcher, set it to Proximity Mines and attach three mines to the Splicer corpse. With that, use Telekinesis to pick up the corpse and then propel it at the Big Daddy. Hit him with a couple of Frag Grenades or use Drill Dash and a couple of Shotgun blasts up close to finish him.
Killing the Elite Bouncer in J. Fischer Gallery
With the Big Daddy out of the picture, Adopt or Harvest the Little Sister and then head up the steps at the southwest end of the room. Collect the Drill Specialist Gene Tonic and the Audio Diary (Gotta Keep it Together) in the backroom up here.
If you've rescued every Little Sister thus far, rescuing this one will yield a reward. Look for a gift from the Little Sisters at the Gatherer's Garden. The gift contains 120 ADAM, 100 Dollars, and the Demanding Father Gene Tonic (Little Sisters continue to gather when interrupted by Splicers).
Goal: Rescue or Harvest Three Little Sisters (Basement Storage)
The Basement Storage area is accessible through the door at the north end of the room -- the one with the carousel at its centre. Head up the stairs to the left of the door to Lamb's Garden and look for an Audio Diary (Dionysus Park's Weakness) at the base of the partially open door. The EVE Expert Gene Tonic is behind the diary.
You can kill the Elite Bouncer here easily with Proximity Mines, just as you did with the others. Hack the Ammo Vending Machine across from the double-door into Lamb's Garden and purchase at least three Proximity Grenades. Then, look for a red, explosive container across from the double-door and pick it up with Telekinesis. Drop the container by pressing X/Square and then equip your Launcher and set it to Proximity Mines. Attach three Proximity Mines to the container, then pick it up with Telekinesis and carry it into Lamb's Garden. If the Elite Bouncer is partially damage, hitting him with this should do him in.
Killing the Big Daddy in Basement Storage
Adopt or Harvest the Little Sister once the Elite Bouncer has been taken care of. If you've adopted her, you can go for the last two gather spots, one of which is in Lamb's Garden. There is a second gathering spot in the carousel room.
Remember that a Big Sister will spawn when you deal with the last Little Sister of the level. She's easy enough to take care of with the Launcher. Just hit her with Frag Grenades and Proximity Mines and she'll fall in no time. Consider backtracking to the Imago Gallery and rescuing or harvesting the Little Sister there, especially if you hacked all of the Turrets and Security Cameras.
Goal: Board the Train to Fontaine Futuristics
Deliver the Little Sister once you're ready to face the Big Sister. Throw down any Mini-Turrets you have and wait for her to come to you. When the Big Sister is dead, fight your way back to the train station to see Stanley.
The final Audio Diary (A Plan) is in the security booth with Stanley. You're faced with another choice here: kill Stanley Poole, or let him live. The choice is easy if you're after the “Savior” achievement or trophy, which is unlocked by rescuing all Little Sisters in the game and sparing all characters when given the choice to let them live or die. Unlike Grace, you won't hear from Stanley again if you let him live.
Once you've made your choice, board the train and flip the switch to complete the level.