"Infiltration" is the second chapter in Uncharted: The Lost Legacy.
Upon starting this chapter, you must first approach a broken ladder and give Nadine a boost, then you'll climb up and slide down the tin roof, and then leap to the fence on the next building. Here, you'll prepare for some difficult climbing. Head to the tin section of the roof and leap to the ledges to the right of the neon sign. To the right is a pipe you must climb, and from there, you'll slide over to the ledge. Leap to the neon sign, then vault over it, then climb up the other two signs to reach the roof. Cross the roof, shimmy along the wall, and then ascend more pipes to get to the next roof. You must continue to jump between the roof until you reach the line with the light bulbs.