The always-lovely Leighton Meester looked retro and ravishing in a lemon-printed dress while shooting the new season of Gossip Girl in New York Thursday.

With her was Roxane Mesquida, who was recently cast as Louis' sister.

It's been reported that the royal character played by the French actress and model will not be pleased with Blair and Louis' engagement. What she does about it remains to be seen.

We'll probably have to wait awhile for that, but it's being set up as one of the big story lines in season five (the arrival of Elizabeth Hurley's character is another).

On this very hot day in New York, we're just starting out ...

An early look at Blair and her newest nemesis.

After scenes of running around in high heels in the heat, the ladies gave their feet a rest by donning flip flops as they chowed down on pretzels with mustard.

We'll post more shots from the set as we come across them all summer!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.