The work opens with a long, luxuriant evocation of Anahuac—Mexico’s coasts, mangrove and palm lowlands, temperate plateaux and snow-capped Orizava—framing an adventurer’s tale set during the Mexican–American War (1846–47). The narrator, an experienced frontiersman recently returned from New Orleans, seeks a commission and, rebuffed, joins a volunteer company raised there. He soon commands a ragged, resourceful band—the mountain hunter Bob Lincoln, the light-hearted lieutenant Clayley, the Frenchman Raoul, the boy “Little Jack,” the Irishman Chane, and the ambiguous Creole Dubrosc among them—and is mustered as captain of the “Rifle Rangers.”

After embarkation and a grand amphibious seizure of Sacrificios that invests Vera Cruz, the narrative alternates camp life—boisterous revelry, drill and peril—with inland scouting. A detachment under Major Blossom and Captain Haller crosses tropical chaparral in search of mules, encountering a series of episodic dangers: a near- fatal ambush, a macabre “skeleton” scare, and a fierce cayman fight. They find the hospitable Don Cosmé Rosales, whose rancho conceals subterranean suites and two daughters, Guadalupe and Maria de la Luz; a cautious romance develops between the narrator and Guadalupe, complicated by jealousy and by Dubrosc’s sinister intrigues as an agent among local guerrillas.

Clandestine forays—once through Vera Cruz’s drains to recover a captive boy, Narcisso—lead into recurring guerrilla warfare: corrals, night rides, captures and escapes. The party is pursued into a narrow cañon where savage bloodhounds are repulsed by Lincoln’s marksmanship and desperate hand-to-hand defence; a mounted band is routed after Lincoln kills a prominent rider and the men employ Indian guile, leaving forage-caps as decoys. Exhausted and rain-soaked, they endure a lightning strike that incapacitates comrades; Raoul’s rudimentary aid and a strange ethological interlude—howler monkeys forming a living suspension-bridge—renew their spirits.

At the National Bridge region they shelter at a contrabandista’s rancho, where the curé Padre Jarauta is revealed as the theatrical leader of the Jarochos. The brigands bind the captives and suspend them head-down; Lincoln’s timely effort and a mounted American relief cut the lazo, rout the Jarochos, and bring summary justice to several prisoners. The narrator is later seized by guerrilleros; imprisonment yields suspense and rescue when a mysterious female hand—connected to the household—passes a knife and a cocuyo to arrange escape; Lincoln effects a daring cut-through and frees the party. Dubrosc’s brutality is exposed and, in subsequent skirmish at Cerro Gordo, he falls.

The narrative closes with the American advance, capture of fleeing Mexican detachments, the occupation of Jalapa, reconciliations, social aftermath and a failed duel cut short by renewed guerrilla action. Throughout, scenes of tropical natural history, camp humor, improvisatory tactics, frontier violence, courtship and honor intertwine, yielding a portrait of war and occupation shaded by moral ambiguity and human ingenuity.