Welcome to Persephone. Walk in a little and past the security desk. Take a right and follow the hallway beyond. Keep walking. And walk some more. Once you get out of the tube, make sure you watch on your left for a Power to the People station. After that there will be one of each vendor on your left. Look at the inventories. There's a reason that they are offering everything under the sun. Make sure you load up on the heavy stuff. Take a right and you'll find a security bot to hack.
After you hack the security bot, head down the hall for a tough fight. Go through the door, walk forward and flip the switch and prepare for a fight against TWO Big Sisters. There's no particularly easy way to do this. There's a healths station and two vending machines in the room to keep you going. Remember that they freeze well so abuse that and your security bots as much as possible. throw out your mini-turrets. Use everything you've got! Remember, this is your last chance to research Big Sisters though. Good luck!
Hopefully you managed to take down the Big Sisters. After that, head into the chamber that just opened. You'll see a cutscene. When you regain control, things will be VERY different.
You are now a Little Sister! There's a vent right in this room and it'll be glowing. Use it to get out of the room. Follow the arrow through the room to the next vent. You may be interested in looking around because things look a lot different. Continue to follow the arrow past Sofia Lamb and throw the switch. Once again follow the arrow through the next room and go through the door. In this room you'll see an "Angel" and like a good little girl you should go and harvest the Angel. Walk up to the body and hit the (A) button to harvest.
Go down the stairs and follow the pathway. You'll then see some stairs leading up and you'll pass a statue of yourself and Aunt Gracie on the left. This statue will show something different depending on whether you killed Grace Halloway or not. Go up the stairs and take your first right into a room and collect the Big Sister body suit. Then go back into the hall, turn right and go out the door.
Turn right after the door and climb through the vent to find another Angel. After you harvest, there's another door leading out. Flip the switch and walk through the door. Walk down the hall and into the room with the fire place. Walk up to the statue of yourself with Stanley and then turn right to find the Big Sister Helmet.
Go up the stairs just beside the desk and into the room with the four talking gentlement. On the left side of this room is another Angel. Follow the arrow out of the room, down the hall and past the door on your right. At the end, turn right and you'll see the weapons of the Big Sister. Grab them and then go back to the door you just passed.
Go down the stairs, then down more stairs, and more stairs and then back down the hall past where Sofia Lamb was earlier. Follow the arrow back to the chamber Eleanor Lamb was trapped. She will become a Big Sister and come set you free.
Now you'll recieve your last plasmid slot and a plasmid to summon Eleanor to fight with you. She's pretty handy in a fight but she takes a lot of Eve. Leave this room and head up the hall to where you fought the two Big Sisters. You'll be confronted by a few slicers including a couple of Brutes. Deal with them however you see fit. Sofia Lamb will say a few words and then follow the arrow out of this room and open the door beyond to enter into Inner Persephone.
