A reclusive giant who lives on Thunder Mountain is falsely accused and pursued by people of a small western frontier town for kidnapping three children of the town.
In the town of Weaverton, signs of a circus are being posted. In the MacGruder's barn, a group of boys are holding a meeting about whether to admit two brothers, Tommy (Chance Michael Corbitt) and Ben (Ryan Todd) to their club, and are dared to climb Thunder Mountain, where it is said a giant lives. Tommy and Ben accept the dare and set out up the mountain. They are caught in a thunderstorm and take refuge inside the giant's oversized log cabin, and find mysterious carved wooden figures the giant has carved. Suddenly, the giant returns and finds the boys hiding under a table, but they escape with one of the wooden figures and go back to town. When the boys reach home they tell Zeke MacGruder their amazing story, but he doesn't believe them. The next morning, they set out with Zeke (Daniel Pipoly) to prove to him they have seen the giant. Tommy and Ben's younger sister, Amy (Noley Thornton) follows the three boys, and almost gets caught in a bear trap. The boys tell her to leave, but she persists and continues following them. The four children watch the giant from the woods moving logs by his cabin, and Zeke is scared and runs back home, but Amy steps out from the woods and introduces herself and her brothers to the giant, Eli Weaver (Richard Kiel). They help him with his chores including helping him plant young fir trees. The boys volunteer to get water for the trees and go in the cabin to fetch a bucket. When they do so, they discover some of Eli's gold nuggets. Tommy puts a few in his pocket, and they go outside and fill the bucket with water. Eli's pet wolf shows up to check out the children and after this, the children return to town. Amy discovers Tommy and Ben looking at the gold nuggets in their bedroom, and they allow her to have a nugget with the promise she won't tell their mother. Amy goes to the general store to buy candy with the nugget, and Hezekiah Crow (Jack Elam) overhears her and says he is an expert in gauging whether a nugget is gold or not, and proclaims the nugget as being "Fool's Gold". In trade, he offers her tickets to his carnival, and she bargains for extra tickets so she can invite Eli. She goes to see Eli and invites him to dinner and gives him one of the carnival tickets. Eli, now clean shaven, comes to the Wilson's house for dinner, and after dinner, repairs their cuckoo clock. Hezekiah Crow's circus parades through Weaverton, hosted by Zeke's father, Mr. MacGruder (Ed Williams). As Eli and Amy watch the carnival parade, which includes an elephant, jugglers, a lion, boa constrictor, clowns, a camel, and an acrobat. The final act, a trained black bear, reminds Eli of the horrible day a grizzly bear (Bart the Bear) killed his parents. At a circus booth, run by one of Hezekiah's sons, Percey Crow, (William Sanderson), Eli throws balls to knock down stacked pins to win a beautiful doll for Amy. Percey puts a rod through the pins so they can't be knocked over, but Eli's final throw breaks the pins and he expects the carnival man to give Amy the doll, but instead he gives her an inferior doll. Amy is disappointed, and Eli grabs hold of the carnival man and lifts him in the air and then drops him on the ground. Eli hands the beautiful ceramic doll to Amy. A crowd has gathered around Eli, and Amy's mother appears and scolds Amy for causing trouble. The crowd shout insults at Eli and Eli crushes the doll's head with one squeeze and warns the town to stay off Thunder Mountain. Amy tries to get Eli to stay, but he leaves for his cabin on Thunder Mountain. At a bar in town, several men (including old man Doc) are playing poker. Hezekiah and his two sons plot to go to Eli's cabin to obtain Eli's gold. Meanwhile, at his cabin, Eli burns the wooden statuette he carved of Amy. Amy goes to see Eli and says she is sorry for what happened in town, and the two are friends again. Eli and Amy go for a walk in the woods and he shows her the biggest tree in the forest "The General". Tommy and Ben go to find Amy and at the cabin are accosted by Hezekiah Crow and his two sons. They kidnap Ben, knock out Tommy, and take Eli's gold. Hearing the approach of a posse, they escape out a window in the back of the cabin, leaving Tommy lying unconscious on the floor. Meanwhile, in the woods, the grizzly (Bart the Bear) approaches Eli and Amy, and Eli fights the bear and knocks it out with a tree branch. Amy runs for the cabin and Eli limps along after her. Amy arrives at the cabin and runs to her mother. The posse do not ascertain what is going on and assume Eli has taken Amy's brothers and set out to catch him. While being stalked, Eli is shot and wounded in the leg by a man of the posse. Eli hides under a pile of leaves and surprises one of the men of the posse who has caught his leg in his own bear trap. He takes the man's gun and takes the trap off the man's leg. The posse burns Eli's cabin as revenge for their mistaken belief he kidnapped the children. Amy and her mom return to town with Tommy. The kidnappers go to the MacGruder's house to steal their belongings and Eli tracks them down and frees the MacGruder's and Ben. Hezekiah Crow tries to trick Eli and escapes out a window. Eli follows him and Hezekiah comes face to face in the dark with the true Giant of Thunder Mountain, the grizzly. Caught between Eli and the bear, he surrenders to Eli and the posse. The movie concludes with the town asking Eli if he would become their Sheriff, and promise to rebuild his cabin. Eli says he must return to the mountain, but leaves as their friend.—Denis Mortenson
In the rural Idaho town of Waterton, signs of a circus are going up. Reports of a man-eating bear-like creature have prompted several hunters to buy some new bear traps.
Meanwhile, at a country house, a group of boys are holding a meeting. Several are telling a story about a giant creature supposedly inhabiting the nearby Thunder Mountain, but the others don't believe them. Later that evening two of the boys, Tommy (Chance Michael Corbitt) and Ben (Ryan Todd) set out to find the mountain, but they get caught in a thunderstorm and barely escape getting hit by lightning (this is what gives Thunder Mountain its name). They take refuge inside a supposedly abandoned house. Whilst there, they find mysterious statues and paintings, one of which is in the shape of a bear and the other in the shape of a giant. Suddenly, the owner of the cottage returns. They boys try to hide from him but he flips open the table they are hiding under and they escape back into the woods. When they reach home, they tell their family their amazing story, but no one believes them.
The next morning, they set out with another boy, Zeke MacGruder Daniel Pipoly) to go back to the cottage and find the answer to what the giant is. Their younger sister, Amy (Noley Thornton) follows them, but almost gets caught in a bear trap. The boys tell her to leave but she persists and continues following them.
Eventually they reach the cottage and Amy manages to make first contact with the "giant", a surprisingly friendly owner named Eli Weaver (Richard Kiel). They help him with his chores including chopping wood and getting water, and while they are there he explains to them that a curse is residing in Thunder Mountain. He also says he makes statues of monstrous creatures he supposedly sees while in the woods. The kids leave the cottage and return home, and as the boys try to picture what the monster creature is Amy goes to the general store of Hezekiah Crow (Jack Elam) to buy some food for Eli, but she has no money. An old man named Doc (Foster Brooks) gives her money and tells her that Eli can use this to help him buy food (as Eli has lived his whole life away from civilization). Returning to Eli's cottage, Amy gives him the money and he asks her what money is. After she explains, he thanks her and she wishes him good luck. Developing a relationship with Amy, Eli makes a statue of her in return for helping him.
That night, Eli stops by the Wilson's house and thanks the family for helping him. They invite him to dinner and whilst there he tells stories of the giant of Thunder Mountain and says that it appears out of nowhere and kills or takes people into the woods, where they are never seen again. He advises the family to be careful and reports of the creature are becoming more and more common. After Eli leaves the house, he walks through the dark woods and supposedly witnesses the giant hunting and killing a deer, disappearing as quickly and mysteriously as ever, into the woods. The next morning, the circus the village was preparing for arrives, hosted by Zeke's father, Mr. Macgruder (Ed Williams). The circus's many performers include a juggling act, a trained lion, a boa constrictor, a long-legged clown act, a camel, a high-jumping acrobat, and two white horses.
The final act arrives, a trained black bear act. This reminds Eli of the day that a giant grizzly bear (Bart the Bear) suddenly appeared out of nowhere and killed his father. His mother rushed out with a loaded shotgun and took a shot at the bear, but her shot only enraged the animal and it killed her too. As the circus continues, Eli tells Amy the frightening story, but she says the menace is long gone. After the elephant act ends, Amy plays some games and wins a doll in a contest. Amy's mother than appears and scolds her for being with a stranger, taking her home. The town becomes angry at Eli thinking he is a big mean stealer and they begin teasing him about his ugliness. To get back at them, Eli crushes the doll's head with one squeeze and warns the town not to mess with his strength. Amy tries to tell him to stay, but he says that he will not visit a town that's disrespectful to him and storms off. The next scene is at a bar, where several men (including old man Doc) are playing a card game. The men talk about Eli and begin to believe that he himself is the monster of Thunder Mountain. Meanwhile, at the cottage, Eli becomes so unhappy about his humiliation that he ends his friendship with Amy out of sadness, destroying her statue.
Despite these events, Amy and the boys have sympathy for Eli, and in an attempt to renew their friendship, Amy stops by the cottage again to bring him food. He accepts, Amy admits her mistakes about bringing him to the village, and the two are friends again. While Eli is taking Amy to Thunder Mountain, Eli asks Tommy and Ben to guard his cottage. However, three thieves led by Doc come to Eli's cottage, knock out the boys, and begin stealing the statues and possessions of Eli. Meanwhile, at Thunder Mountain, Eli shows Amy the biggest tree of them all, a huge sequoia. Eli explains that this tree has been in the family for generations and will continue to bloom as long as he is alive.
Just then, a giant grizzly bear appears out of nowhere and attacks them. Eli reveals that this and the tree are the "giants" of Thunder Mountain and orders he to run. As she takes refuge in a tree, Eli fights off the bear with a stick and knife, but is wounded in the process. The bear chases Eli for a while before giving up and walking away, Eli orders Amy to continue without him. Meanwhile, the cottage raiders have taken all the statues and are about to leave when Amy arrives. Amy tells them to give the statues back but they refuse and tie her up along with her mother who comes by to help her. They then go on a hunt for Eli as they think he a ruthless monster who deserves to be killed. Unable to outrun them, the wounded Eli's only defense is to bury himself with leaves and play dead, hoping to fool the men. The plan barely works, with the men just missing Eli buried in the leaves. The leader gets caught in his own bear trap, giving Eli time to escape. Eli takes his gun and has a chance to kill the man, but due to what Amy has taught him about friendship he refuses and lets the man go. Impressed by Eli's act of mercy, the hunter orders his men not to pursue Eli and they head back to the village, release Amy and her mom, and care for the wounded Tommy and Ben.
However, when Tommy tells his story of how he and his friends got to know Eli, the villagers mistakenly think that Eli was the one who injured Tommy (the men who did lie about it), and, believing Eli is a threat to the village, burn down his house. Amy agrees to find Eli a new home farther away from the villagers and the twos set off again. Meanwhile, Doc and the other thieves wrest a confession about Eli from Zeke (who lies that Eli was killed in the fire) and threaten to kill him and his family if they don't answer. However, Eli and Amy arrive and mount a rescue operation. Eli manages to trick Doc into thinking that he's surrendered and forces Doc to run out of the house in fear. As Eli and Amy untie Zeke and his family, Doc goes into the woods to follow Eli but is captured. When Eli threatens to feed him to the grizzly but doesn't, right in front of the other men, they develop sympathy for him and arrest Doc for lying and burning Eli's home. Later that evening Amy and her family say goodbye to Eli as he leaves to find a new home, but Eli promises Amy that they will meet again sometime.
The movie ends with Amy telling (as an adult, narrating), that she will never forget Eli as a friend.
