Out in the Temple courtyard, Holly and Cha-Ka are boiling a large pot of water to make vegetable soup for dinner. They go inside to fetch the vegetables, but when they return, the pot is missing from the brazier. Later, when Uncle Jack and Will return with firewood, Holly relates to them her story of the mysterious theft. Harmless as it may seem, Jack decides to take the incident seriously, since the thief was bold enough to enter their compound while Holly and Cha-Ka were around. He decides to scout the area alone.

While searching through the jungle, Jack approaches a tree hiding a Great Plains Indian. The Indian tries to flee but makes a noise, so Jack reflexively trips the stranger. The American Indian expects to be finished off that moment, and is surprised to find that Jack is not the man hunting him down. Responding to Jack's interrogation, the Indian identifies himself Lone Wolf, the Medicine Man of the Nez Perce tribe; his people are suffering from an epidemic of fever, and he was trying to return to them with White Man's medicine. Lone Wolf admits to stealing the boiling water, since he needed it to make Indian medicine for himself; he was thrown from his horse when he rode into a giant, whirling dust storm, and the medicine remains on his lost horse. Lone Wolf is at first defensive when Uncle Jack shows concern about the Indian's health, but Jack assures the Medicine Man that his intention is simply to help a fellow human being in need.

Back at the Temple, Will and Holly curiously question their guest, who reveals that (to him) the year is 1877, and that he was educated by Nez Perce Chief Joseph. Just then Cha-Ka returns from the jungle, to report hearing a "terrible creature" making a whinnying sound. Lone Wolf realizes that the creature is his horse, so he insists on going out to find it. Their guest is still weak, so the Marshalls insist that he rest; Will offers to go out and catch the horse.

Out in the jungle, Will soon finds the horse, which is standing in a small clearing, tied to a tree. Out from the foliage comes a U.S. Cavalry man, pointing a rifle at Will and accusing him of horse theft. The man identifies himself as Captain Elmo Diggs, and explains that the tied horse was bait for a trap to catch an English-speaking Indian. Will vocally realizes that the Captain is looking for Lone Wolf, so he suspiciously asks him why he is tracking the Indian. The Captain replies that Lone Wolf is a "rotten, thievin' savage", who stole U.S. Government property; he demands that Will lead him to Indian immediately.

Captain Diggs instructs Will to hold the horse's reigns and lead the way, but when he tries to mount the horse, he collapses from weakness. Will seizes the rifle, only to find that it is empty; the exhausted Captain admits that he is out of ammunition. Will rushes over to help the feverish Captain, who explains that there is an epidemic at his fort. He then goes on to ponder how, after chasing Lone Wolf into a roaring twister, they ended up in the surrounding jungle. Will proposes that they ride together on the horse, allowing the Captain to lean on him for stability.

At the Temple, Holly worries what is taking her brother so long; Uncle Jack announces that he'll go after him if he is not back soon. On their journey to the Temple, Will and the Captain encounter Torchy; the Captain believes that his fever is causing hallucinations, so Will doesn't bother to convince him otherwise. Lone Wolf and the Marshalls know that Will has finally returned when they hear the horse whinnying outside. They all come out to greet Will, though when Lone Wolf sees Captain Diggs, he heads back inside. The Captain introduces himself while he stumbles off the horse, so the family helps the sick Cavalry man into the Temple.

While Uncle Jack helps Captain Diggs over to a straw bed to rest, the Captain notes how the fever has taken "a lot of good men". Lone Wolf cannot bear to hold his tongue, and adds "what he means, Mr. Marshall, is a lot of good white men." The Captain and Lone Wolf get into an argument about the rightful ownership of the "stolen" medicine, but Uncle Jack insists that they stop arguing for the sake of the Captain's health. Lone Wolf explains to Uncle Jack that the U.S. Government allotted medicine to both the cavalrymen at the fort and the people of the Nez Perce tribe. When the fort had used up its allotment, the Nez Perce offered its consignment of medicine to the people at the fort. Since the epidemic raged on, Lone Wolf went to retrieve the medicine that he believes still belongs to his tribe. When Holly questions Lone Wolf why, as Medicine Man, he cannot cure his people by traditional methods, the Indian explains that the epidemic is far too vast for one man to conquer with the old ways. "The White Man's medicine," the Indian explains, "can be everywhere at once."

Cha-Ka fetches more water at the swamp, where he has the usual run-in with LuLu. Though he continues to get even weaker, Captain Diggs insists on getting back to his fort with the medicine. Uncle Jack realizes that the Captain is moribund, so he pleads with the Medicine Man to do what he can. When Holly also pleads, Lone Wolf agrees to help, but on the condition that in exchange he gain the Captain's horse. Uncle Jack points out that the horse is not his to give, but agrees to the deal when the Indian describes the horse as a small price to pay for a human life. Lone Wolf insists on taking the horse now, since it will allow him to gather more quickly the necessary ingredients for the medicine. Lone Wolf promises to Jack to return in one hour, then speeds off just as Will walks in; after Jack explains the Medicine Man's rush, his nephew wonders if the Indian will ever return at all.

Lone Wolf rides the horse through the jungle, staying clear of Grumpy who is bellowing nearby. Meanwhile, at the Temple, bed-ridden Captain Diggs moans to the Marshalls that they never should have let the Indian take his horse, since it is the only way for either of them to get back. The hour soon passes, so Uncle Jack heads out into the jungle to track the Medicine Man. Jack soon hears the whinnying horse, and finds Lone Wolf trying to hide behind a boulder from Grumpy. (This a sorry scene where existing animation footage was reused to make a very poor fit: not only is it highly questionable that Lone Wolf would try to hide himself and a large horse behind a small boulder in a clearing, but there is no way that Grumpy would simply stand there bellowing and confused.) Uncle Jack calls over quietly to Lone Wolf promising to rescue the Indian but also reminding him that he will owe a favor. By catapulting a bowling-ball sized rock to the far side of the clearing with a supple sapling, Jack manages to divert the tyrannosaur's attention. Lone Wolf claims that the terrible lizard had pursued him before he could find what he needed, but Jack plays it safe by insisting that he aid the Indian in gathering the ingredients to make the traditional medicine.

Captain Diggs resists having the Medicine Man perform his ritual curing, believing instead that the Indian will poison him to keep him from ever returning to the fort. Will points out that Lone Wolf cured himself, and that he alone is the Captains only hope for a cure. The Medicine Man begins his ritual by moving a large grey fluffy feather over the Captain's body; he then spins a voodoo-like doll suspended over the straw bed. Lone Wolf creates a burst of colored flame by flinging a pinch of "magic" powder into the fire of the brazier. Time passes, and the Medicine Man feeds the curative potion to the weak, sweaty, face-painted Cavalry captain. When night falls, Lone Wolf sits outside in the courtyard rhythmically beating a small drum with stubby stick. Late into the night, Will finds that the Captain has awakened and is feeling better. The Marshalls hit the sack to get what little sleep they can, since it will be daylight soon. Just then the Captain see Lone Wolf step inside; the two of them share a solemn gaze.

Early the next morning, Captain Diggs arises to sneak out to his horse and retrieve something from his pack. He then shuffles into the Temple to where Lone Wolf is sleeping, where we hear only the sound of clanking chains and the Indian's plea "why are you doing this?". The Marshalls soon arise to meet Captain Diggs outside, where he holds Lone Wolf in heavy iron chains. The Captain insists that the Lone Wolf is his legal prisoner, that he has orders to take the Indian back to the fort for trial. Holly and Will question the cavalryman's behavior after the Medicine Man had just saved his life; the Captain claims that he is not proud of what he is doing, but he has an obligation as a soldier to turn Lone Wolf in. In a strong but compassionate tone of voice, Uncle Jack states his firm belief that the Captain's greatest obligation is to Lone Wolf for saving his life. The soldier realizes the truth of Jack's statement and hesitantly decides to set Lone Wolf free; the Marshalls praise him for making the right decision.

Before the Medicine Man heads out on his new horse, Uncle Jack asks him if he intended to return from gathering the medicine ingredients. Lone Wolf looks solemnly at Uncle Jack to simply say, "what do you think, Mr. Marshall?". Just as the Indian begins to lead the horse away, Captain Diggs voices that without his horse, he will never return to the fort. Lone Wolf stops the horse, turns and gently nods, inviting the soldier to ride with him on his journey. Captain Diggs thanks the Marshalls for all their help, then mounts the horse in back of the Medicine Man. Uncle Jack bids the Indian goodbye, letting him know that the favor has been fully repaid.

That evening around their campfire, Holly explains her theory why Lone Wolf stole the boiling pot of water: he needed it to make medicine to cure his own fever, and he couldn't build his own fire without risking it being seen by pursuant Captain Diggs. Holly asks her uncle if he believes the two men will return to their own time; Jack is reluctant to say yes, but emphasizes that they are trying together. Will picks up on the topic of going home, and ends the series by singing one last bad song.