The narrator, Arthur Wright, and his friend Hugh Dutton visit their former classmate, Dr. John Pollard at his combination house/laboratory. Pollard, a classic mad scientist, has been conducting research into the question of what causes the mutations that drive evolution. Pollard informs them that he has determined that cosmic rays are the source of the mutations, and that he has decided that bombarding himself with heavy concentrations of cosmic rays will cause him to evolve into a future version of humanity.