DESMOND HARRINGTON RETURNS AS JACK BASS / BILLY BALDWIN GUEST STARS – Chuck invites Jack (Harrington) to town to thank him for saving his life, but finds the trip doesn’t go exactly as planned. Blair and Dan attempt to consummate their new relationship — but unexpected roadblocks get in their way. Meanwhile, Ivy finds an unlikely ally in William (Baldwin) in her quest to be accepted on the Upper East Side, and Nate is hopeful a new investor will save his newspaper. Blake Lively, Kelly Rutherford and Matthew Settle also star. Joe Lazarov directed the episode written by Annemarie Navar-Gill.