Nineteen-year-old Mabel Dongchen, accompanied by her uncle - the old sailor Cap - and two Indians (The Shooting Arrow and his wife June Dew) have been wading through endless American wilds from New York for a few days into a small English fortress on the shores of Lake Ontario. They are on their way to Mabel’s father, Sergeant Dunham. Having overcome another “veto” - a place where trees turned upright are piled on top of each other, travelers notice the fire smoke. During the war (and the battles between the British and French from 1755 to 1763 were practically silent), random encounters are always dangerous - a small detachment with great caution scouts out who is cooking this dinner: friends or enemies? Fortunately, friends: The Pathfinder (the same one, known to us earlier under the names St. John's Wort and Hawkeye, Nathaniel Bampo) with a constant companion Chingachgook and a new friend, a young man, Jasper Westorn. (Indians allied to the French appeared in the vicinity of the fortress, and Sergeant Dunham sent a small but reliable detachment to meet his daughter.)

The remaining few miles were remembered by Mabel for a long time. Possible thanks to Jasper’s mastery, a descent in a cake over a waterfall and rifts, victorious (under the guidance of the Pathfinder) skirmishes with superior enemy forces, the desperate courage of Chingachgook - this is not forgotten. The sergeant can be doubly satisfied: his daughter was delivered safe and sound, and, in addition, along the way, as Dunham had hoped, she could feel feelings for his old friend Nathaniel Bampo. Indeed, Mabel was imbued with ... subsidiaries! The nearly forty-year-old Ranger for a nineteen-year-old girl is more likely a father than a possible husband. True, Mabel herself is not aware of anything yet; the sergeant decided without her and, without asking his daughter, managed to convince a friend that he - courageous and honest - could not fail to please the girl. And even the shooting competition, when Jasper "beg" for his victory, did not open the Ranger, who had feelings for whom and whom. He himself - on his mountain - fascinated by Mabel and trusting her father, falls in love in earnest. To the point that when it comes time to change the guard at a secret post, the Pathfinder allows himself to neglect the duties of a scout and does not go along the lake with Chingachguk, but leaves with a girl and a sergeant in a small single-masted boat - cutter.

Before sailing, the fortress commander confesses to Sergeant Dunham that he received an anonymous letter accusing the captain of the cutter Jasper Western of betrayal. Dunham will carefully monitor the young man and in which case remove him from captain's duties, entrusting the ship to his wife’s brother, the experienced sailor Cap. And, despite many years of acquaintance with Jasper, the sergeant begins all of him - the most harmless! - reinterpret actions in their own way. Finally, the burden of responsibility becomes unbearable for Dunham - he removes Western from commanding the cutter and trusts the ship to Cap. The brave sailor bravely gets down to business, but ... - "lake" navigation has its own specifics! Not only does nobody know anything about the location of the desired island - it’s not very easy to just “ride” on the cutter! The storm that has raged in earnest drives the little ship right on the stones. And, probably, if it were not for the persuasion of Mabel and the Pathfinder - not even for a minute, by the way, who doubted Jasper's honesty - Cap and Dunham would rather die “right” than save themselves not by the rules. But pity for the daughter was shaken by the stubbornness of the sergeant - he returns command to Western. The amazing art of a young man saves the ship.

While the cutter, at the last moment detained by anchors a few meters from the stone ridge, was waiting for excitement, the sergeant - supposedly for hunting - invited the Pathfinder and Mabel to go ashore with him. Having landed, the group broke up: Dunham headed in one direction, Bampo with a girl in the other, Ranger does not seem to interfere with any explanation, but, decisive and brave in battle, he is shy with a girl. Finally, having overcome the excitement and somehow coped with an unexpectedly numb language, he explains. Mabel at first does not understand, realizing - embarrassed. She herself, to a well-aimed shooter and a skilled warrior, feeds feelings of a different kind. If not entirely affiliated, then only friendly. And no other. Gratitude, gratitude - to the girl it seems that this is not enough for a happy marriage. On the other hand, she does not want to disappoint either the father or the Ranger. The question, however, is posed directly - it is impossible to avoid a direct answer. With all possible tact, carefully choosing the words, Mabel refuses to become the Ranger's wife.

Upon the return of the "hunters," the cutter is removed from the anchor - good, the storm subsided and the excitement subsided. Further sailing - under the command of the well-knowing Jasper Lake, is accomplished unmatchedly more calmly. The sergeant, who took command, prepares an expedition - the British intend to intercept from the French the "strategic" goods delivered to those Allied Indians: guns, gunpowder, lead, knives, tomahawks. The ranger along with Chingachguk goes on reconnaissance. At night, the garrison, led by a sergeant, campaigns. The blockhouse - cut down from Thick logs, with loopholes instead of windows with two-story fortifications - remains in the care of not too skilled soldiers: corporal, three soldiers, Cap and Lieutenant Muir. (The latter, volunteering for Mabel, volunteered.)

The girl is restless. She worries about her father and - for some reason! - for Jasper suspected of treason. To calm the alarm, Mabel walks around the island. Suddenly, from behind the bushes, a girl calls out a quiet familiar voice - June Dew. It turns out that her husband, Blasting Arrow, is a long-time secret agent of the French, openly sided with them and led the Indians about to attack the island. June Dew advises Mabel to take cover in a blockhouse and wait out the attack there. Unreasonable anxiety is replaced by fear - what now awaits the father? What about her? The June Dew reassures: becoming a second wife of the Striking Arrow is a great honor. But such a prospect seems Mabel worse than death. And there is no one to consult with: the uncle and the lieutenant stocked up somewhere, and the corporal is a stubborn Scot! - wants to know nothing about some Indians there. The girl is trying to convince him, but the corporal is full of contempt for the "savages." Mabel sees how, suddenly jumping up, the Scot falls face down. At first, without understanding anything, she rushes to the rescue, but the corporal exhales, having managed to wheeze: "Hurry to the blockhouse." The girl takes refuge in the building and locks the door - the Indians, from behind the bushes, having shot dead soldiers who rushed to the aid, take possession of the island. At night, the Pathfinder sneaks into the blockhouse - the frightened Mabel is slightly encouraged. But not for long - the detachment, led by a sergeant and returning with victory, is ambushed. The ranger, using the darkness, manages to drag the seriously wounded Dunham into the blockhouse. The subsequent attack Nathaniel strongly reflects, shooting several Indians about to set fire to the fortification. The next morning, the winners offer surrender - The Pathfinder refuses. A cutter appears - the situation changes dramatically: the Indians caught in the crossfire, losing their dead and wounded, scatter around the island and hide. Now the captain of France, who led the recent winners, is already asking for surrender. Having agreed on favorable conditions for themselves, the Pathfinder agrees with Jasper. Disarmed Indians leave the island. All this time, Lieutenant Muir, who has been in captivity, has been insisting that there is evidence in defiance! - the traitor is Jasper. Suddenly Shattering Arrow with the words: “Where are the guns, where are the scalps?” - stabs the lieutenant with a knife and starts off. The French captain confirms that in fact, the traitor was murdered by the Indian Mur.

Dying of his wounds, Sergeant Dunham managed to bind Mabel with a promise that the girl would give her hand to the Ranger. Then she - grateful to Nathaniel and not having the strength to refuse her dying father - agreed. But ... the sergeant was buried, Jasper in a trembling voice says goodbye to her, something oppresses the girl. The pathfinder, delighted with the consent, suddenly sees clearly: at last he is revealed to him who is really superfluous in the formed triangle. Having talked in private with Jasper, he calls up Mabel and, with difficulty restraining his tears, says: “The sergeant left me as your protector, and not as a tyrant <...> the main thing for me is your happiness ...” The girl tries to object, but her babble is unconvincing - expressed words more perfect does not agree with those hidden in the depths of the soul; the tongue says: "Nathaniel" - the heart beats: "Jasper." Youth, alas, as always, is right: The Pathfinder is a voluntary victim of his own generosity! - saying goodbye to lovers, lingers on the island. Something necessary in this world has been lost to them forever, but something is no less necessary in that! - probably acquired. And if not, then all the same the essence remained unchanged: by anyone, but as a tyrant, the Pathfinder cannot ... - only a defender ...