The poem recounts the tragic fall of Roderick, last Gothic king, whose private passions and political failures coincide with an invading force and betrayals that overturn his realm. It interleaves scenes of solitude, penitence, romance, and battle, following his interactions with figures such as Florinda, Count Julian, Pelayo, and others, and depicting monasteries, camps, and mountain fastnesses. Themes include guilt, crisis, fate and repentance, with meditative passages on virtue and loss. The structure alternates dramatic episodes and reflective interludes, culminating in defeat, resistance in the mountains, and the personal consequences of leadership and moral error.