Assassin's Creed 4: Black Flag's PlayStation-exclusive levels have been shown off in more detail by developer Ubisoft.The content features an older Aveline de Grandpré, the heroine of last year's PlayStation Vita title Assassin's Creed: Liberation, and will be written by that game's lead scribe Jill Murray.The hour-long "short story" is divided into three bonus missions for PlayStation 3 and 4 owners, and will pick up a while after Liberation's conclusion."It's a ways forward so Aveline is a bit older," AC4 lead writer Darby McDevitt explained in a new post on Ubisoft's official blog. "It's not directly related to the end of her story. If Assassin's Creed 4 is like a novel, Aveline's missions are like a short story."PS3 and PS4 owners will access the content via Black Flag's modern day section, set within Templar company Abstergo Entertainment."The present-day is set in Abstergo Entertainment - which is this fun, hip company to work for... at first," McDevitt continued. "You are able to access the Aveline stuff because your coworkers are working on retrieving different genetic memories from all kinds of different people."Last night Ubisoft revealed more details of Black Flag's multiplayer portion, specifically itsnew co-operative Discovery mode.