After the scene, talk to the couple outside the magic shop to start another sub-scenario. You can't do anything else at the moment so save the game if you want then head to the plaza to proceed with the festival. Watch the following scenes. You'll learn about your next destination due west of Florem.
After the scenes, rest at the inn to continue DeRosa's sub-scenario. For the dedicated walkthrough of this sub-scenario, refer to this link.
To start yet another sub-scenario, leave the city and enter again. Upon entering the city again, the group will bump into a person who hurriedly left without saying anything. The group will pick up a note containing a warning. For the dedicated walkthrough of this sub-scenario, refer to this link.
When you're ready to continue with the story, head to the west and find the Twilight Ruins.