According to Mass Effect 3's Lead Writer, Marc Walters, a Citadel plot line that was cut from Mass Effect 2 will appear in the game. The Citadel was not nearly as prevalent in Mass Effect 2 as it was in the original; very seldom did a quest actually require you travel back there. When...

After completing the Lost Child Side Quest, head on over to the Light Tower (the area where you first encounter Groose) and speak with Parrow to learn that his little sister Orielle has gone missing. Jump off the ledge and call on your trusty Crimson Loftwing and fly Southwest towards Fun-Fun...