The narwhal is the unicorn of the sea, a pale-colored porpoise found in Canadian Arctic and Greenlandic waters and rivers. Now, a group of scientists, explorers and adventurers traces the narwhal’s path north to its summer home. Their mission is to capture a snapshot of the arctic ecosystem –for future generations to use as a benchmark. But the high arctic throws them one dangerous obstacle after another. To keep up with the migrating narwhal, they must navigate the thickest sea ice in generations. In the end, their journey leads them to the frozen edge of a changing world.