Credit: Courtesy of The CW

Gossip Girl is back on Monday with the countdown to the season finale—and it looks like trouble is brewing once again on the Upper East Side. Serena gets suspicious when Dan and Blair (shown at left in an Oscar de la Renta gown and Swarovski necklace) start spending a little too much time together, so she teams up with Charlie to find out what’s really going on. Meanwhile, Nate helps Raina search for her biological mother, only to be forced to choose between friends when he learns the truth. Tune in Monday 9/8c to catch your weekly dose of Upper East Side drama, and click through the gallery to see more chic looks from the episode.