The clip opens with a black screen before we see Elsa race across an ocean of water that she tries to freeze. But the ice doesn't hold up and Elsa falls down, winding up underwater. She manages to swim back up to the surface again but she also sees a horse on her way up.
Then, we see her standing with Anna when a troll rolls over to them.
“Elsa, the past is not what it seems. You must find the truth,” he cryptically warns her while a montage begins to play of the adventure that lies ahead. “Go north, across the enchanted lands and into the unknown. But be careful. We have always feared Elsa's powers were too much for this world. Now, we must hope they are enough."