Morgan Leah is the eldest son of Kyle Leah, a landholder who bred beef cattle. His ancestors had once been Kings of Leah, but the monarchy was overthrown almost 200 years before his time, after the Federation expanded northward and took over all the Highlands.
Unwilling to let the occupation of his homeland go unavenged, Morgan tormented the officials ruling Leah with practical jokes, possibly including the destruction of the Leah ancestral palace. Morgan also made friends with members of the Dwarf Resistance, and helped them whenever he could. Like members of the House of Leah before him, Morgan was a friend and acquaintance to members of the Ohmsford family, most notably the brothers Par and Coll Ohmsford, and to a lesser extent Walker Boh and Wren Ohmsford.
Morgan meets up with Par and Coll while they are passing through Leah after fleeing Varfleet. He decides to accompany them to the Eastland to find Walker Boh and travel to the Hadeshorn. Along the way, Morgan rediscovers the magic of the Sword of Leah during a battle against a Shadowen and slowly develops the yearning for the sword's magic that his ancestor Rone had possessed.
After Par receives his charge from the Druid Allanon to recover the Sword of Shannara, Morgan decides to accompany him and Coll on their quest and suggests gaining the aid of Padishar Creel. Morgan follows the brothers to Tyrsis, where the Sword of Leah's blade is shattered while he and Padishar attempt to escape from a group of Shadowen. Morgan stayed with Padishar for a time, assisting him within the Free-born base camp at the Jut in Parma Key along with his friend Steff and Steff's lover Teel. Morgan eventually discover that Teel is a Shadowen who had betrayed the Free-born to the Federation. With the help of Steff and Padishar, Morgan kills Teel with his broken sword.
Morgan decides to leave the Free-born and set out to find the Ohmsford brothers, from whom he had been separated in Tyrsis.
Along the way, however, Morgan is arrested by the Federation in Culhaven after rescuing Granny Elise and Auntie Jilt from the Federation workhouses. He is broken out of his jail cell by the assassin Pe Ell at the behest of the elemental Quickening. Pe Ell takes Morgan to Quickening, who recruits him on her quest to take back the Black Elfstone from the Stone King. They meet up with Walker Boh at the remains of Hearthstone and travel to Eldwist to recover the Black Elfstone.
During the journey, Morgan and Quickening end up falling in love, and her willing death at the hands of Pe Ell in order to restore the lands of Eldwist hits Morgan especially hard. However, as a parting gift, Quickening restored the broken Sword of Leah while restoring the land.
Morgan resumes his quest to find the Ohmsford brothers, meeting up with the Free-born fighter Matty Roh, whom he begins to grow close to. He later rescues Wren, who was now Queen of the Elves, from the Shadowen. Morgan then accompanies Par, Coll, Walker, Damson Rhee, Rumor the moor cat, and Matty into the depths of Southwatch to destroy the Shadowen for good. After the Shadowen are destroyed, Morgan reconnects with the Dwarf Resistance and helps repel the the Federation from the Eastland. He also marries Matty Roh.
130 years after his time, Morgan's great-great-grandson Quentin Leah would accompany Walker Boh and Bek Ohmsford on a quest to the land of Parkasia. Centuries after that, Quentin's descendant Paxon Leah would become the protector of the fourth Druid Order, under the leadership of the Ard Rhys Aphenglow Elessedil.