The film opens in the city of Gothia, a smoky industrial metropolis where steam-powered dirigibles are the primary mode of transportation, and where a terrible flesh-eating plague is decimating the population.

The protagonist, royal navigator Jasper Morello (Joel Edgerton), is deployed by the government to distribute mobile weather beacons along the route of his next voyage.

He has difficulty concentrating on the task, guilt-stricken over the recent death of one of his crew members which was caused by a mistake in his calculations ("one degree can be a very large distance – enough to unmake a man").

Their airship the Resolution is also carrying a passenger, the eccentric Dr Claude Belgon (Helmut Bakaitis), a "controversial biologist" searching for a cure for the plague, and motivated by a thirst for fame.

While exploring there, Jasper is attacked by a large bug-like creature, which they manage to kill, despite the protests of Claude, who had wanted to capture a living specimen.

Knowing that he may not survive, prior to reaching home, Jasper reassures his wife that he will be, with "The great company of souls, riding the borealis to eternity" (a reference to his previous observation, of such a sight).

Scenes featuring characters were composed out of a variety of materials, including card cut-outs which were then scanned and manipulated in Adobe Photoshop, and also various found objects.