In classical Greece, and again in middle ages Rome, a mysterious bright light illuminates iconic historical scenes. At the Woodstock Festival in 1969, a third incident occurs in which two people witness a figure in a tree illuminated by the same bright light. A student historian researches these occurrences and believes they are cosmic in nature. He connects with the two witnesses and they begin to unravel the mystery. They are stymied in their attempts to get answers by a benign, but frightening, response caused by a small remnant of the phenomenon, the 'Mcguffin.'