Max Payne continues through the apartment to find Mona.
See No 'Us' In This for background information.
Fire on the Third Floor
Well, run straight forward through a white door (there's a painkiller bottle tucked next to a bench on your right). Kill the cleaners that are waiting for you, but watch out for their Grenades. One of them will drop a Painkiller. Run all the way up as long as you can and get the ammo and painkillers from all of the crates. Now run down again until you hear a man screaming. Run into or shoot the wooden piece that is blocking the door, and let this bum follow you further down the stairs. He used to be a police officer, after all. You will get to some smaller stairs once you're done with the bigger ones. At the bottom, go through the 'EXIT' door, and talk to the prostitute. Turn around and walk down the corridor and kill the three cleaners that emerge at the far end. That Sniper Rifle you picked up earlier may come in handy here.
Enter the basement by using the door that the cleaners came from. At the bottom of the basement, use the valve there to turn of the gas to stop the fire torching the apartments. Raid the lockers for some painkillers and Desert Eagle ammo. Then, with the bum and the prostitute still following, head upwards again, and kill the three new cleaners on your way up. Now, go back to the 3rd floor, where you first met the bum when he was trapped behind a door. At the end of the corridor, go to the left into the room that has been destroyed by fire (303, across from Max's still-burning apartment). If you go right into the bathroom once you're in here, you can get two painkillers. Jump out of the leftmost window, equip the Kalashnikov, and shoot the cleaners that will appear below you. Use the gap to walk as far as you can, and more cleaners will appear. Kill them all, and jump onto the scaffolding at the end of the ledge. Use it to go all the way to the top, onto another ledge, and then jump across a gap to yet another ledge.
Now, jump down to the chain link scaffolding a new stairway. It will collapse a level at a time: be careful, and drop down to a new stairway to the right, and when this one collapses, drop down to one on the left. At the bottom, you will meet lots of cleaners jumping out of a van, use Ingrams (and a Molotov if you have them: throw it early enough and you can light most if not all of them on fire) to take them all out. Once they're all dead, the van will drive away, so pick up the ammo as fast as possible before the cut scene starts.
Jim Bravura goes mad over what he says is a kindergarten of people going berserk and killing each other. He takes pills to cool himself down. Max thinks about what really happened, and the fact that Vladimir told him that Vinnie Gognitti was behind all this. Well, back at the office, Max sees that Mona has tried to call him. Winterson catches Max while calling back, and tells him to not do anything stupid. Max gets Mona's home address.