There's a pact! And of course, not everyone's happy about that. At Mount Weather the group springs to action. And Clarke has some problems with ghosts.
This episode is a slow paced one, but the better for it, because it keeps the tension at a high level, and adds a new layer to the proceedings: are Grounders and Ark people going to be able to work together or is the ticking bomb going to explode? Both teams offer many perspectives and ideas, from Raven's desire for revenge, to Kane's thoughtful words, and Alycia Debnam-Carey's Lexa way too smart Grounders leader. In a society full of violent and dangerous people, she seems too cool to had gotten into power. The show follows the it's-just-like-this explanation of not explaining it, and we can accept it, as she is a smart character.
But that her and Clarke are both leaders, just teenagers, is somewhat difficult to explain. Kane's words at the beginning of the episode telling how both groups are leaded by children at least makes the characters recognize it. As Machiavelli said, fortune favors the younger, because they have more energy and desire.
It's pretty obvious that more tensions between Grounders and Ark people will happen. How next episodes deal with this will show if "The 100" can keep its quality.
And with the lives of Monty, Jasper and the others on the line, will they arrive on time to Mount Weather? "The 100" is treading now well known sci-fi territory. But the production values and the acting and plot development keeps it being great.