To the Tower is the ninth chapter of Drake's Fortune. Nathan Drake and Elena Fisher continued their search through the Drowned City for a vantage point to enter the customs house.
After navigating further through the flooded ruins, Nate and Elena reached a drop-off point. Nate proceeded alone to reach the tower while Elena returned to the customs house, intending to meet him there. Following several skirmishes with Eddy Raja's pirates, Nate reached the summit of the tower. He used a cable as a makeshift zipline to slide through a hole in the customs house roof. Once inside, he regrouped with Elena by opening the main doors, and the two continued their search for an escape boat.
Walkthrough[]
Nate and Elena en route to the tower.
This chapter continues the jet ski sequence from the previous one. Maintain momentum while eliminating pirates and detonating floating barrels. Follow the linear path to a large gate and shoot the chains on either side to lower it. After docking the vehicle, Elena departs, leaving you to explore the ruins solo. Three pirates—one armed with a Moss - 12—will ambush you immediately; neutralize them and collect the two Mk-NDI grenades in the vicinity before advancing.
Nate protecting himself from more pirates.
Swim through the narrow canal to the next area. Enemies will engage you head-on; once you reach the end, take cover or hang from the ledge to pick off targets safely. Collect the grenades from the crate in the lower-left corner. Climb the stairs, jump across the balcony to the broken wall, and navigate the pillars to reach the top of the locked gate. Drop down to engage the next wave of combatants.
Take cover immediately, as pirates with a Moss - 12 and a Wes - 44 will ambush you at close range. An enemy wielding an M79 grenade launcher is stationed in the first opening on the right; eliminate him quickly. Use the M79 or nearby building ledges as cover to clear the plaza in front of the tower. Reserve some M79 ammunition for the final group of pirates that exits the tower simultaneously.
Nate ascends to the top of the tower.
Enter the tower and dispatch the remaining pirates with melee attacks. Locate and pull the lever to position a chain, then climb it to the second floor. Use the white-marked handholds to reach a second lever, then navigate across the small platforms to reach the final chain. After defeating the pirate at the top, climb the stairs to the summit. Press 
at the wire to zipline into the customs house.
Inside, descend the stairs to the main entrance. Shoot the lock off the door and press to let Elena in. Be efficient, as taking too long will result in a mission failure if Elena is killed. Once reunited, the next chapter begins.