Boris Johnson travels through France, Spain, Egypt, Israel, Syria, and Turkey to test a familiar claim: that Christianity and Islam have been locked in permanent conflict since their earliest contact. This first episode of a two-part series covers the years 632 to 1492, starting with Muhammad's death and the campaigns that took roughly half the old Roman empire's territory for Islam within eighty years. Johnson visits the cities and monuments left by that expansion and talks through the civilization it produced, one that preserved and extended Greek philosophy, mathematics, and medicine while Latin Christendom lagged behind. He looks closely at how Muslims, Jews, and Christians actually lived alongside each other under Islamic rule, arguing the record is messier and more cooperative than the clash narrative allows, before tracing the buildup of grievances and politics that led toward the Crusades. The film's case rests on specifics rather than slogans: named cities, dated conquests, and the everyday coexistence that complicates the simple story of two civilizations at permanent war.