Six months have passed. It is a winter's day at Joyous Guard (Lancelot's castle) and Lancelot and Guenever are standing in the Great Hall. They have been under siege for months now. The two are discussing how Lancelot killed Gaheris and Gareth; he still cannot understand how he could have done it. Lancelot now has to fight the King, his best friend—all because of Gawaine's grief and Mordred's wicked refusal to allow Lancelot to atone for his mistake. The pair considers what they can do, if perhaps there is a way for the two to atone and make it up with Arthur. Guenever suggests that they atone to the Pope—and ask him for forgiveness. If the Pope grants them forgiveness, the whole kingdom will have to obey it.
Lancelot and Guenever—and Arthur along with them—are trapped. The pair are literally being laid siege to in a castle, but this literal entrapment is representative of their current plight. They have been found guilty of treason and thus if they return to Arthur he will have to execute them; and, moreover, Lancelot has killed Gareth and Gaheris and so the Orkney clan will never allow peace while Lancelot is alive. That Lancelot can't understand how he could have killed Gareth and Gaheris highlights the depth of his love for Guenever—he was focused solely on rescuing her and nothing else—and the blindness that love casts over him and, therefore, its destructive power. Just as the lovers are trapped, Arthur has found himself in an inescapable situation where he must uphold justice, yet if he does, he must kill Lancelot and Guenever.