I think Clarke has a good idea where Luna is because at the end of season 1, Lincoln had started to lead "the 100" to her village before they fell under attack and had to retreat back to the drop ship.

I really liked this episode a lot…until the execution of Lincoln. Not only was it a terribly violent and upsetting visual, and the end to a likable character, but nobody, not even Pike, could be that believably fool-hearty to think it was the right thing to do or that it would help his agenda. Pike went from stubborn…