King Henry the IVth was planning a holy crusade to Jerusalem to atone for the death of Richard II. His plans are thwarted by reports of war on the borders of England. Owen Glendower, a Welsh Chieftain has defeated the English army and captured Edmund Mortimer, it's commander. Better news arrives from the Scottish border where young Hotspur (Henry Percy), has defeated a great Scottish soldier, the earl of Douglas.
This victory is marred by the behavior of his rakehell eldest son, Prince Hal. Hal is the same age as young Hotspur . Hotspur is busy defending England. Hal however amuses himself with London lowlifes. His particular favorite debauched associate is Sir John Falstaff a fat, drunken, hedonistic coward.