Physicist Ben Longmier and his engineering team head into the Alaskan backcountry to test hardware for a new kind of rocket engine, one built to run on plasma, the ionized fourth state of matter, rather than chemical fuel. Instead of a launch pad, they use helium balloons to carry sensitive components up through radiation-heavy layers of the atmosphere, checking whether the electronics can survive conditions close to what a real spacecraft would face. The film follows the team onto mountain glaciers for the balloon launches themselves, a low-budget substitute for orbital testing that still produces real data and real failures. Footage inside the effort is intercut with imagery of the Sun and geomagnetic storms, the same solar activity that makes radiation shielding necessary in the first place. The engine itself is still years from flight, and the episode is really a portrait of that earlier, uncertain stage: a small private team trying to prove a propulsion concept works before anyone will fund it at scale.