Melancholy in Porto:  

Part1 (Centre of Porto): get loot from dead bodies in water in middle area and on both sides under opening in brick walls, now open front doors to main building, pick open mail boxes on left for loot, use Keeper Telmos Key in your inventory (on normal difficulty) to open one of these mail boxes, go left in hall and use Keeper Telmos key again to open first door on left, go into bedroom, open chest near bed to bring back to Keeper Telmo his ancient Greek mask,

pick open doors on bottom and top levels of this building to get loot, each room contains some loot, search the corners of each bathroom and each bedroom well, when you have finished getting loot go back down to first level and open white door in corner to enter small room with water hole in the center, drop down into water and swim up to bathroom, get loot from this bottom level, open door down here to outside area with wooden table, hop over wall then hop over walled area with patio behind it for some loot on a table, get the remaining loot on this side then hop back over the wall, go back inside the house and go up the wooden stairs, enter kitchen to see if everything is ok with Aunt Matilde,

go back down and back through the water hole to get back to the main building, now open back doors between some plants to enter patio area with long white table, mantle up and over the broken section in the wall next to fallen plant, enter warehouse and open one of the middle doors, go up steps and open door to enter another house, get loot and go to bedroom with large white mask on the wall, pick open chest next to bed to get flux spheroid to find sample of new Quimic mixture,

go back down to warehouse, you can open another door in the warehouse that leads to an outside area with wall, hop over wall and go up steps for some more loot, now go back through warehouse and hop back over broken section, if you still need some more loot you can mantle up each spot on this broken section and hop to balcony up high here with some more loot, go back into main building and back through front doors, go back to where you started to end level 

Part 2 (Melancholy In Porto):  go through this area picking up loot along the way, open lockers for loot and go up steps in corners to rooms at top with loot, make your way to a staircase next to Marquee Cola machine that leads to a brown wooden/glass door at the top, enter this room and take Mr. Belmiro diary to find out who caused the explosion in the main reactor,

go back down and look for big machine with ladder going up it, climb to top of this machine to find secret loot, climb back down ladder and enter small enclosed courtyard right next to this machine with two ghost guards with swords patrolling it, remove crates in corner along side back wall, crawl through opening to enter school grounds, get loot from this area then enter school, go right in hall and open classroom door on right, frob window then hop into another outside area, get loot bag from behind crate, mantle back up in through window and continue getting loot from the bottom level, go upstairs and look for lab room, take Prof. Quim notes book from floor next to chair to find out what Prof. Quim has to do with electrical nuclear central ,

when you have satisfied loot requirement go back down and back through opening in wall, go back to where you started to end mission