On the Paris streets level, there is a hostel, you have access to this level after ascending from the sewers. Find it and enter it. To the left of the reception desk you'll find a stairway which will take you to the first floor. You will find two doors, for two separate rooms respectively. At the top of the stairs, turn 180 degrees and follow the floor around a right hand corner. Keep following the corridor and you'll reach some kind of balcony with two sofas. On your right there should be a service tray and on top of it a nanokey. Take it and go back to the two doors. Use the key on the left one. Once you're inside the achievement will pop, along with a message from a known character. You can go up the small staircase and find a credit chit, a datapad and a bioelectric cell on the nightstand.