The action takes place in the 1850s. On the Texas prairie there are vans going – it’s moving from Louisiana to Texas ruined planter Woodley Poindexter. He is accompanied by Henry’s son, daughter Louise and nephew, retired captain Cassius Colhoun. Suddenly they lose track – before them scorched prairie. The path of the caravan is indicated by a young rider in a Mexican suit. The caravan continues to move, but soon the rider appears again, this time to save the settlers from the hurricane. He says that his name is Maurice Gerald, or Maurice Mustang, because he is a hunter for wild horses. Louise falls in love with him at first sight.
Soon, in the Casa del Corvo, where the Poindekssters settled, a dinner party should be held on the occasion of a housewarming party. In the midst of the triumph, Maurice the Mustang appears with a herd of horses, which he caught on the order of Poindexter. Among them is a mustang of a rare mottled color. Poindexter offers a large sum for it, but the Mustang refuses money and presents the mustang as a gift to Louise.
After some time, the commandant of the fort near the Casa del Corvo arranges a reciprocal reception – a picnic on the prairie, during which it is planned to hunt for mustangs. Maurice is the conductor. Hardly the participants of the picnic are at rest, as the herd of wild mares appears, and the speckled mare, galloping after them, takes Louise to the prairie. Maurice fears, as if the speckled, after catching up her herd, did not try to get rid of the rider, and rushes in pursuit. Soon he catches up with the girl, but they face a new danger – they are galloped by a herd of wild stallions, extremely aggressive at this time of the year. Maurice and Louise have to flee, but they get rid of persecution only when the Mustang kills the leader with a well-aimed shot.
The heroes are left alone, and Maurice invites Louise to her hut. The girl is pleasantly surprised to see there books and other little things that testify to the erudition of the owner.
Meanwhile, burning with jealousy Cassius Kolhoun follows the tracks of Maurice and Louise and eventually meets them. They walk slowly alongside, and jealousy flares up in him with renewed vigor.
In the evening of the same day, men are drinking in the bar of the only hotel in the village “Na Pralola”, which is kept by the German Franz Oberdofer. Colhoun offers a toast, offensive to the Irishman Maurice
Gerald, and at the same time pushes him. In response, he pours out a glass of whiskey into his face. It is clear to everyone that the quarrel will end in a shootout.
Indeed, right there, in the bar, there is a duel. Both participants are injured, but Mustanger still manages to put a pistol to Kolkhane’s temple. He forced to apologize.
Because of the wounds, Colhoun and Maurice Mustang must comply with bed rest, but Colhoun is surrounded by care, and Mustang languishes in a miserable hotel. But soon the baskets with provisions begin to arrive – these are the gifts of Isidore Covarubio de Los Llanos, rescued by him once from the hands of drunken Indians and in love with him. This becomes known to Louise, and, tormented by jealousy, she adjusts the meeting with Mustang. During the meeting between them there is an explanation in love.
When Louise is once again going on a horse walk, her father forbids her to leave on the pretext that the Comanches have gone out on the warpath. The girl surprisingly easily agrees and begins to get involved in archery – with the help of arrows she exchanges letters with Maurice Mustang.
The exchange of letters is followed by secret night encounters in the courtyard of the estate. The witness of one such meeting is Cassius Colhoun, who wants to use this as a pretext to deal with the Mustang with the hands of Henry Poindexter. Between Henry and Maurice is a quarrel, but Louise persuades his brother to catch the Mustang and apologize to him.
The furious Colhoun tries to set Maurice Diaz, who has his scores with the Irishman because of Isidore, but is dead drunk. Then Colhoun himself goes after Maurice and Henry.
The next day it turns out that Henry disappeared. Suddenly, at the gate of the manor appears his horse with traces of gore. They suspect that Comanche attacked the young man. The officers of the fort and the planters are on the lookout.
Suddenly, the host appears. He says that the night before the Mustang paid the bill and moved out. Soon Henry Poindexter appeared at the hotel. Finding out in which direction the Mustanger left, he rode after him.
The search squad travels through the forest clearing, when suddenly, against a background of setting sun, the horseman without a head appears before the eyes of the gathered. The detachment is trying to follow its tracks, but the tracks are lost in the “chalk prairie”. It was decided to postpone the search until morning, and the major, the commandant of the fort, reports of the evidence found by the Spopler-Spangler, which excludes the involvement of the Indians. Suspicion of the murder falls on Maurice Gerald, and everyone decides to go to his hut in the morning.
At this time in the Casa del Corvo comes the hunter Zebulon Stump, a friend of Maurice. Louise retells to him the rumors about the death of his brother and the involvement of Maurice Gerald. At her request, the hunter goes to Mustang to save him from lynching.
When the hunter is in the hut, Tara dog comes running with Maurice’s business card tied to the collar, There it is written in the blood where it can be found. Zeb Stump appears just in time to save a wounded friend from a jaguar. Meanwhile, Louise sees a rider, similar to Maurice, from the roof of the manor. After jumping after him, she finds in the woods a note from Isidore to Maurice. Jealousy flashes up in the girl, and she decides, contrary to propriety, to go to her lover to check her suspicions. In the Mustang hut, she meets Isidore. At the sight of the rival, she leaves the hut.
Thanks to Isidore, the search party easily finds the home of a Mustang, in which Woodley Poindexter discovers his daughter. He sends her home. And on time, because the assembled are ready to lynch the alleged killer, mainly due to false testimony from Colhoun. She manages to delay the execution for a while, but the passions flare up with renewed vigor, and the unconscious Mustang is again ready to hang on the branch. This time it is saved by Zeb Stump, who demands a fair trial. Maurice Gerald is taken to the guardhouse at Fort Innge.
Zeb Stump follows the trail of the drama participants. During the search, he manages to see a rider without a head from a close distance, and he is convinced that this is Henry Poindexter.
Waiting for the court, Colhoun asks Uncle Louise’s hand – he is his debtor and is unlikely to be able to refuse. But Louise does not want to hear about it either. Then at the trial, Colhoun talks about her secret meeting with the Mustang and about the quarrel with Henry. Louise is forced to admit that this is so.
From the story of Maurice at the trial it becomes known that after the quarrel they met Henry in the woods, reconciled and exchanged capes and hats as a sign of friendship. Henry left, and Maurice decided to spend the night in the woods. Suddenly he was awakened by a shot, but he did not attach any importance to him and fell asleep again, and in the morning he found the corpse of Henry with a severed head. To deliver it to his relatives, the corpse had to be put into the saddle of the Mustang that belonged to Maurice, since Henry’s horse did not want to carry this gloomy burden. The Mustang himself mounted Henry’s horse, but did not pick up the reins, so he could not control it when he carried it. As a result of a frenzied race, the Mustang hit his head against the branch and flew off his horse.
At this moment, Zeb Stump appears, who leads with him and the headless horseman. He saw Colhoun trying to catch a rider to get rid of evidence, and makes it clear in court that Colhoun is a murderer. The proof is the bullet extracted from the corpse with the initials of Calhoun and the letter addressed to him, which he used as a wool. The reassured Colquhoun tries to escape, but Maurice the Mustang catches him.
Colhoun confesses to the murder, which he made by mistake: he aimed at the Mustang, not knowing that he had changed clothes with his cousin. But before hearing the verdict, Colhoun shoots a Mustang, who is rescued from death by the medallion donated by Louise. In despair, Colhoun shoots himself a bullet in the forehead.
Immediately it turns out that Maurice Gerald – the owner of a large fortune. He marries Louise and ransoms from the successor of Calhaun Casa del Corvo. With them, the servant Felim O’Neill and Zeb Stump, who supplies game to the table, live happily. Ten years later, Maurice and Louise already have six children.
Soon after the wedding of Maurice and Louise, Miguel Diaz of jealousy kills Isidore, for which he is hung on the first bitch.