We're leaving the docks and go to the area of "The Stormy Docks Dojo". Opposite its entrance, go up the red wall, head right and cross the big pink advertisement.
Stay on the roof and continue your way over the roofs. There is a catapult on the roof at the far back. Use it to get to the roof with the Scroll. Here use Dual Swords to open and switch to the other character to get it.
Go up to the wind mill. There you can hango onto it to get on top, where you use the zip line to reach a window with silver bars. Blow them up with Explosives.