The narrative introduces Professor Lidenbrock, a renowned yet deeply eccentric scholar of mineralogy at the Johannium in Hamburg. Living with his nephew Axel, the Professor is characterized by his intense focus and impatience. Axel describes his uncle as a "very stubborn man" whose life is entirely "wrapped up in his work," specifically the study of "minerals, rocks, and geography." Despite his academic prestige and the family's respected name in Germany, Lidenbrock’s lack of pedagogical patience often leads to frustration among his students, as he possesses "very little interest in helping others learn" and frequently flies into a "rage if he thought a person misunderstood him."
The story shifts on May 24, 1863, when Lidenbrock returns home in a state of uncharacteristic excitement. Ignoring the domestic concerns of his housekeeper, Martha, he summons Axel to his study. The catalyst for this urgency is an old, "tattered" book he acquired that morning. Lidenbrock describes the item as a "priceless gem," revealing it to be a 12th-century Icelandic manuscript. While Axel initially dismisses the book as uninteresting, the Professor clarifies that it is not written in standard Icelandic, but rather in "runes," a script featuring "small, stick-like figures" that appear "impossible to understand" to the untrained eye.
As Lidenbrock delves into a lengthy, passionate lecture on the history of the runic language—a subject he is clearly obsessed with—the plot takes a sudden turn. A small piece of paper, measuring "five inches wide and three inches long," slips from the pages of the ancient book and lands at their feet. This scrap is covered in more "runes," shifting the focus from a historical artifact to a potential puzzle. Lidenbrock’s immediate reaction—studying the paper with intense scrutiny and laying it down "very carefully" on his desk—signals the gravity of this discovery.
The discovery of this mysterious note serves as the inciting incident for the entire saga. Axel notes the profound significance of the moment, stating, "Whatever does it mean?" was the question that would "lead us on the adventure of a lifetime." The interaction between the uncle’s scientific rigor and the cryptic nature of the runic document sets the stage for a journey that transcends the boundaries of traditional mineralogy. The text masterfully frames the Professor's obsessive nature as the primary engine for the impending expedition, transforming a quiet study in Hamburg into the starting point of an extraordinary exploration.