The alliance eventually becomes a love affair. The homophobic barons are against the Gaveston's hold on the king. Also, to make matters worst, Gaveston is a commoner. All conspire to rid Gaveston of the king. This is done with great effect at the end of the first act, however, the king finds a new friend, Spencer, who becomes the king's paramour.
Civil war occurs between the king and the barons in which the barons are defeated.
Isabella and her son, the future King Edward III, flee to France and form an army to overthrow the king. This is done successfully and Edward 2 is imprisoned where he is tortured and degraded. Montimer sends an assassin to kill Edward 2 by the horrible means of a red hot poker and he is skewered on a spit. This we see on stage to horrible effect. Things do turn worst for Isabella and her lover Montimer.