First Knight is an attempt to portray the story of the love between Lancelot and Guinevere.  It takes one of the oldest stories told about King Arthur.  According to Caradoc of Llancarfan’s Life of St. Gildas, Arthur’s wife Guinevere was abducted by a warrior called Melwas.  This story was elaborated in the late twelfth century by the French poet Chrétien de Troyes, who invented a series of obstacles that Guinevere’s new rescuer, Lancelot, had to overcome before he could rescue the queen.  The most important are the cart that Lancelot rides in when his horse is slain (a source of shame, since the cart is a tumbril, used to transport criminals to execution) and the perilous bridge Lancelot must cross, made from the blade of a sword.  Chrétien also invented the notion that Lancelot and Guinevere were in love, a notion that later became central to the legend.  In a somewhat rationalized form, all of these motifs make an appearance in the movie First Knight.