When the outlaw crew of an old airship gets pulled into a search and rescue job by a powerful politician, they find a themselves teaming up with two deadly peacekeepers and wading through a conspiracy encompassing strange derelicts, private militaries, otherworldly technology, and one peculiar man at the center of a plan that's been a long time in the making.

On a mountaineering expedition gone awry, Alex and his friends stumble upon something they never expected to find: a mysterious door hidden beneath a glacier. Driven by the excitement of discovery, Alex’s friends are determined to return, but they are not the only ones who are interested in what the door might contain. When his friends go missing, Alex will have to brave the dangers of the mountain, evade the Historical Acquisitions Agency, and use all his wits and resources if he is going to unlock the secret of the door and find a way to bring his friends home.