This Codex provides basic lore on previous Elder Scrolls games. The quotes included do not actually come from in-game books.
After trapping Emperor Uriel Septim VII in an alternate plane, Imperial Battlemage Jagar Tharn assumes the Emperor's identity, and rules without care as the provinces wage war. The ghost of Ria Silmane frees a hero from the depths of the Empire's dungeons and guides his search for the Staff of Chaos, a potent artifact which Jagar Tharn has broken in eight parts and hidden. The hero journeys to eight well-defended citadels in eight different provinces, recovering the Staff's pieces. Then, armed with the reforged Staff, the hero confronts and defeats Jagar Tharn in the labyrinths beneath the Imperial Palace, and the Emperor is returned to the throne.
From a complex weave of arcane plots, Imperial intrigues, and personal betrayals, an agent of Uriel Septim resolves two historic feats: the laying to rest of the ghost of treacherously slain King Lysandus of Daggerfall, and the reactivation of Numidium, the titanic iron golem once used by Tiber Septim to forge the Empire. The agent who won the Mantella from the plane of Aetherius and gifted his patron with the Totem artifact decided who should command Numidium, and who would shape the future of the Empire.
The Impostor Jagar Tharn betrayed the Battlespire, the war college of the Imperial Battlemages, to the legions of Daedra Lord Mehrunes Dagon. Two trainees trapped in the Battlespire escaped by fighting their way through daedric gates until they came to the citadel of Lord Dagon, where, by a subtle trick, they cast the Daedra Lord into Oblivion. Having lost Lord Dagon's support, Jagar Tharn's plot to supplant the true Emperor was doomed to fail.
In 2E 864, the Redguards of Hammerfell rose in rebellion against the Imperial administration of Provincial Governor Amiel Richton. The Restless League, led by Cyrus and Iszara -- brother-and-sister agents of the province's hereditary rulers -- destroyed the Imperial fleet in Stros M'kai harbor and routed the Legion garrison. With Admiral Richton dead, and Stros M'Kai in rebel hands, Emperor Tiber Septim was forced to sue for peace on terms favorable to Hammerfell.
In 3E 427, with Imperial authority weakened by questions of succession, the already shaky Imperial administration of Morrowind was threatened by the re-awakening of an ancient curse beneath the giant volcano Red Mountain, also called "Dagoth-Ur." An Imperial courier marked by the stars, born on a certain date to uncertain parents, came to Morrowind a stranger and outlander, and lived to become one of that nation's most enduring legends.