Feeling the pressure to make her first Waldorf Designs fashion show a success, Blair (Leighton Meester) must rely on help from an unlikely source, but some unexpected scheming causes a scandal on the runway.  Serena (Blake Lively) discovers that befriending Steven’s (guest star Barry Watson) daughter Sage (guest star Sofia Black-D’Elia) is trickier than she thought, especially when she is forced to put her issues with Blair aside to make Sage happy.  Nate (Chace Crawford) publishes Dan’s (Penn Badgley) first serialized article causing a stir and producing a serious threat.  Meanwhile, Chuck (Ed Westwick) begins to look into the clue that Amira (guest star Andrea Gabriel) left behind, which may help uncover what Bart (guest star Robert John Burke) is hiding.