In the last chapter, you stole the key to the display case where Sir Francis' Ring is being held, and as the sun is setting down, you watch an open window in the museum from the roof across, planning to steal the ring.

Okay, Museum's closed.

Use the rope to make your way across the roof to the museum. Climb up to yet another roof and over some glass panels, reaching some wood planks. Jump on the planks and hang from a lamp post. Jump down to the roof. Enter through the window.

Head to the display case. The ring is inside. Take out your key and unlock the glass case. Take the ring, as well as the Cipher Disk.

Suddenly Sully and Marlowe show up! You try to escape but you are surrounded. You hand over the disk, but hide the ring. Marlowe demands you give it to her. Then you manage to slip under a display case and escape with the ring.

Climb up the stairs. You will reach a door but it is closed, dont waste time trying to open it. Climb to the window above it and go through it. The goons will break through the door so hurry and reach the next set of stairs. If they catch you, the mission will fail. Climb and head to the roof, open the door, then go past the gate. The goons will grab you by the legs. Tap the square button quickly to escape their grip. Jump onto the roof and keep running, dont look back.

Go over an air condition and jump to the roof across. Keep running and run around to another roof and climb the balcony. Climb over a dumpster to reach another red roof with three chimneys on it.

The thugs will start shooting at you at this point.

Jump across to another small balcony and hop on the small roof panels. Those panels will collapse as soon as you land on them, so QUICKLY jump to the next platform. Get up on the roof  and up on the air conditioner and jump onto the next roof. The thugs will almost get you, but Sully will rescue you. Keep running and jumping roofs, when you get to a corner with a window, climb to a roof above. Climb over the fans and jump to the far roof across. You will start sliding down. Tap X button quickly. You will catapult into a kitchen in the house across. Marlowe's goons will be after you, so keep moving. Get to the bedroom, go over the bed, and jump out the window to the outside terrace. Continue running, jump to the next platform by using the lamp post to proper yourself.

The goons will keep shooting at you. Run fast and jump to the balcony across (the one with the bench). Dont go Around the corner, or one of the thugs will catch you. instead, jump down to the roof below. Struggle with one of the goons and push him off the roof. Another thug will arrive and aim a gun at you. Pick up the gun that the other guy dropped, on the roof near you. As he is about to shoot you, Sully will shoot him in the back and save you. He will take you some place safe and give you food.

He will introduce himself as Victor Sullivan. He will ask you what's so special about the ring. You will tell him it belongs in your family, and you were just taking it back. Show him the ring, as if he was going to take it from you he would've taken it by now. He will read it: "Sic Parvis Magna" - it means "Greatness from Small Beginnings" That was his motto. Queen Elizabeth gave it to him in 1581, when he got back to England after circumnavigating the globe. That's when she made him a knight.

You will tell him that the disk you took was not an Astrolabe, it was some sort of decoding device. Drake thinks the decoder is a key to a big treasure. Marlowe has the decoder now, but it wont do her much good without the key. Sully will offer you to be your Mentor. You will introduce yourself to him finally, as Nathan Drake, or "Nate". Sully sees great things in your future together. Great things.