A fragmentary aviator's journal describes an inventive but solitary pilot's experiments with high-altitude flight and growing concern after a fellow airman is found decapitated. The manuscript, missing several folios and stained with apparent blood, combines technical notes, personal recollection, and a chilling account of ascents into the stratosphere where the author encounters unknown airborne life forms that attack aircraft. He records increasing premonition, public attention, and meticulous arrangements suggesting foreknowledge of disaster, then narrates violent encounters that mutilate victims and culminate in his own unexplained disappearance, leaving investigators to puzzle over the remaining torn pages and forensic traces.