Chuck (Ed Westwick) hosts a “Saints and Sinners” masquerade party at the Empire Hotel. At the party, Dan (Penn Badgley) and Nate (Chace Crawford) don’t know what to make of Serena’s (Blake Lively) strange behavior and mixed messages. Blair (Leighton Meester), pictured here in a Bensoni dress and Swarovski necklace (left) and a Natori slip and Carlos Falchi clutch (right), sets her sights on becoming the face of Anne Archibald’s (guest star Francie Swift) foundation for girls. But Anne is concerned that Blair’s friendship with Chuck Bass may be problematic. Tune into the CW at 9 p.m. ET Monday night to see all of the amazing fashion!