Four exceptional astronomers celebrate 50 years of work and friendship on a return road trip in the southwestern United States, recapturing youthful adventures and recounting each other's influences on the most exciting period in astronomy’s history. Roger the instrument-maker, Donald the theoretician, Nick the visionary, and Wal the observer. Together they represent the most productive period astronomy has ever had. They helped build the world’s biggest observatories and made revolutionary discoveries about the evolving universe, discoveries that have the power to change the way humanity sees itself. Alison Rose’s film is a funny, insightful, humbling and intimate portrait of friendship, as the men reflect on how their profound work on the universe has reflected back on the individual, affecting their sense of religious faith, how life may have purpose, and what is knowable and unknowable.