Team Plasma attacked Opelucid City (Black 2) and froze up the place. I must have mashed A few too many times and now they're gone and I have no idea where to go. All unexplored towns are blocked off for increasingly implausible excuses and I don't see anything else in Opelucid city to do. I beat all the plasma grunts and some named Plasma big-shot, they took the DNA Splicer, and I beat the guy blocking the exit (but I see nothing of interest past that exit).
Where do I go after getting the 7th badge? I obviously need to go stop Team Plasma but have no idea where to go now that they've left.