Jim and Artie are riding through the woods to determine why every living thing has disappeared in the vicinity. The y discover that all of the fruit-bearing vegetables are dead, but all other vegetation is fine. They ride to the Indian tribe at Bright Star to find out if they know anything. However, they find an armored knight on the road ahead of them, blocking their path. It advances on them, immune to their bullets. Thugs dressed as Robin Hood’s Merry Men emerge from the woods and quickly disarm the agents. The knight advances to them and welcomes them to Sherwood Forest.
The Merry Men take Jim and Artie to a medieval camp. The agents are escorted into a tent where Antoinette is playing the lute for… Dr. Miguelito Loveless. He explains that he is posing as Robin Hood, Lord of the Forest, even as he sneezes due to hay fever. The agents ignore Loveless, goading him into telling them his plan. He explains that he engineered a famine on the Bright Star tribe, insisting that he wants them to accept him as their benefactor. The agents attack the thugs, making short work of them. They run outside and ride away, while Loveless laughs in triumph and assures Antoinette that he meant to let them go. When they reach Bright Star, they’ll find trouble waiting for them.
Jim and Artie ride into Bright Star and receive a hostile reaction. The chief steps forward and they explain that they are there about the famine. He tells them to go, insisting that the government left them to starve. Jim finally convinces him to meet with them, but they’re interrupted when Loveless and his men arrive with a wagon of food. The Indians give them a friendly reception until they discover that he’s brought sand. Loveless explains that his “master,” the Lord of the Forest, is unhappy with them. He accuses the tribe of disloyalty by harboring Jim and Artie. Loveless demands that the chief prove his loyalty by killing them. Braves attack the agents and Artie manages to escape into the woods. However, Jim is outnumbered and brought down. Loveless orders the Indians to take him prisoner and sends two trackers to find Artie. Before he departs, he then tells the chief to slowly torture Jim to death.
The chief has his braves throw Jim into a tent, where he manages to knock over a lamp and secretly take a piece of grass. Jim points out that Washington sent food but the Bright Star tribe sent it back, but the chief says the canned food was spoiled. The Lord of the Forest sent Loveless with food, but Jim note they also sent tools and seeds that the Indians have refused. Now they are living in decaying tents while no one works. Jim tries to warn the chief that the “little warrior” is evil, while the braves place a crossbow on a stand in front of Jim. The chief refuses to listen and goes to his people so they can pray to banish Jim’s spirit when he dies. Before he goes, he explains that the leather string on the trigger is wet. As it dries, it will pull the trigger and kill Jim. Once he’s alone, Jim uses the glass shard to cut himself free.
At the medieval camp, Loveless suffers from a cold and Antoinette tends to him. He complains that the chief hasn’t killed Jim yet, and that the tribe should be obedient to him by now.
As night falls and the Indians dance and pray, Artie slips into the camp disguised as an Indian woman. Inside the tent, Loveless enters through a hidden tunnel, carrying a spray bottle. Jim invites him to gloat, and Loveless explains that his special formula creates a film that kills plant life. If he increases the dosage, it will kill animals and even Man. When Jim points out that children will die as well, Loveless shrugs off his concern, insisting that children can’t understand pain. He tells Jim that he’ll soon be beyond the pain and leaves, and Jim goes back to cutting himself free.
Artie slips away from the dancers and goes to his captured horse. He takes some powders from the saddle and mixes them in a bowl with some food, and then rejoins the dancers. He then goes to the guards in front of Jim’s tent and offers them the drugged food. They quickly collapse and Artie gets inside to knock the crossbow away. However, the dancing braves spot the unconscious guards and go inside, only to discover that Jim and Artie have slipped way. They go to the horses to stop the agents, and Jim grabs the chief’s knife and tells him to back away. The chief’s wife turns around, revealing Loveless in a papoose and armed with a crossbow.
The next day, Loveless and his men return to their camp and find another chief who demands to see the Lord of the Forest. After his men tie up the agents, Loveless goes into the tent and enters the suit of armor, which is constructed to make Loveless appear man-size and give him enhanced mechanical strength. Meanwhile, Artie and Jim calculate that Loveless must have 10,000 Indians that are dependent on him for food and will obey his every command.
The armored Loveless steps up as the old chief and his men enter the tent. The old chief reminds him of his promise to rebuild their land and asks how he plans to overwhelm the white man. He warns that his braves won’t fight for the Lord of the Forest unless they receive an explanation. Loveless promises to send “Robin Hood” to show them how they will regain their country and orders them out. The old chief and the others reluctantly leave, and Loveless emerges from the armored suit.
Loveless has his men untie Jim and Artie. When the braves come over, Loveless explains that he will show them how to kill palefaces. His men take Jim and Artie through a fake tree into his underground lair. He then demonstrates his explosive powder on a model of Washington D.C. Loveless uses a model balloon to demonstrate how he will drop the powder on Washington, destroying it. He prepares to use a slingshot to fire a pellet of the explosive at Jim, who challenges the Lord of the Forest to kill him. Loveless refuses but the old chief insists and agrees to fight once the Lord of the Forest wins. However, he warns that if Jim wins, they will give his loyalty to him. Jim warns Artie that he’s never even seen a mace before.
While Loveless and Antoinette sing, Artie and Jim wait under guard. They realize that Loveless must be the man inside the armor and poses as a knight to gain the tribes’ respect. However, Jim warns that he can’t just expose Loveless, but must earn their respect as a fighter. Inside the tent, Loveless puts a bit of his explosive powder in the head of one of his maces. When it hits Jim, it will explode with lethal results. Loveless tells Antoinette that they’ll give the exploding mace to Jim. When she worries, he assures her that he knows what he’s doing.
The armored Loveless comes out of the tent and Jim and Artie step forward. Loveless offers Jim the rigged mace, but the agent suspects a trap and chooses the other. However, when Loveless inadvertently bumps the rigged mace and tells his thug to watch out, the agents realize that it’s rigged with explosives. After a brief fight, Jim disarms Loveless and the mace falls to the ground, exploding. As Antoinette runs to Loveless’ side, the chiefs order their braves to attack Loveless’ Merry Men. Antoinette gets Loveless out of the armor and they duck into a hidden compartment in the forest.
Antoinette and Loveless go to the underground lab and prepare a balloon for launch so they can destroy the forest. Loveless releases the balloon, laughing triumphantly. Above, Jim grabs a bow and shoots down the balloon. It falls back into the lab and explodes, setting the lab on fire. Loveless and Antoinette enter a hollow log as the flames close in on them.
Later, Jim and Artie go through the ashes but find no sign of Loveless. They assume that Loveless and Antoinette died in the fire and depart. Once they’re gone, a rabbit hops out of the hollow log.
Aboard the Wanderer
, Jim and Artie are sparring when the train stops. They received a telegram to pick up a package at the next station. Inside they find a note saying it’s from their unknown admirer. A small model of a knight rises up and a recording of Loveless and Antoinette singing plays from its face.