Unlike Shakespeare's earlier history plays, King John does not portray a providential movement of history, where everything happens for a reason on a predestined path to a moral conclusion. While the play focuses on some of the historical events of King John's reign, it also delivers less narrative drive than plays such as Henry V. Events in the plot disrupt the connection between intention and outcome throughout the play--the characters are thwarted by historical accident and adversity, making King John more a pragmatic representation of political events than a story shaped according to aesthetic ends.
The main conflict turns on John's efforts to retain the crown against claims that he is not the rightful heir to the throne. The opening scene of the play shows a struggle over inheritance between the Bastard and his younger brother, which leads to a surprising conclusion that being a bastard is not a barrier to inheritance. However, the Bastard then renounces his inheritance, choosing to be a landless knight.
Agreements come and go throughout the play. The English and French battle to stalemate while seeking the allegiance of Angers, then band together to destroy the town, before ending their quarrel and sparing the town by negotiating a marriage between heirs of France and England. But this resolution is transitory; the messenger from the pope, Pandolf, excommunicates John and insists King Philip of France, just joined to John's family in marriage, go to war against John.
Philip supports Arthur as the legal heir to the throne, so John thinks he can secure his hold on the throne by ordering Arthur killed. However, this assassination turns his lords against him and brings on an invasion by the French. Yet Arthur's executioner has actually spared Arthur, so John tries to reverse the situation. But Arthur dies in an accident that is interpreted as murder, and John's lords join the French army. John tries to undo the coming battle by belatedly submitting to the pope, but this has no effect. John's lords return to him when they hear the French plan to kill them.
Climactic battles take place offstage or not at all, derailed by last-minute treaties or a succession of armies lost at sea and drowned in tides. John dies away from the battlefield, poisoned by a monk angered by his robbery of the monasteries, making an undramatic ending based on circumstances barely portrayed within the scope of the play. The king's son appears conveniently at John's deathbed, just in time to announce the arrival of a peace accord from France. The ending seems orthodox enough--a dead king is succeeded by his son and heir--but it feels quite shaky, given that prospects for peace seemed so tremulous before John's death and that John was never proved to be the rightful heir anyway.
The play dramatizes several topics that would have interested Shakespeare's contemporary audience: a struggle with the papacy, the danger of invasion, and the debate about legitimate rule. These same topics were hotly debated during Queen Elizabeth's reign. Yet King John differs from Shakespeare's other histories. It portrays the thirteenth century rather than the fourteenth or fifteenth, and unlike other historical plays that were part of a series, this play stands alone. Other historical plays focused attention on the balance of power between the nobility and the king, and gave account of popular unrest; this play, by contrast, completely marginalizes the populace and does not attribute much strength to the nobles.