Dar is a warrior who can talk to the beasts. He is forced to travel to Earth to stop his evil brother from stealing an atomic bomb and turning their native land from a desert into, well - a desert.
In the land of Arok, the nomad warrior Dar (Marc Singer), known as the Beastmaster for his magical ability to control animals, is taken prisoner by the evil warlord, Arklon (Wings Hauser). Dar refuses to divulge the location of rebel forces and is sentenced to death. The executioner is interrupted by Dar's pet tiger, Ruh, while his ferrets, Podo and Kodo, chew through their master's bonds, allowing him to defeat Arklon's soldiers. When the warlord fights back with a magical laser device called the "Key of Magog," Dar's eagle, Sharak, tears at Arklon's face, enabling the Beastmaster to escape.
Sometime later, rebel forces are led into a narrow gorge by a treasonous witch named Lyranna (Sarah Douglas). After Arklon's army annihilates the rebels, Lyranna offers to make him the most powerful man on planet Earth. Lyranna speaks in modern English slang which confuses Arklon and she tells him that she has been to a place where others imagine beyond space and time.
Meanwhile, Dar encounters a deformed swamp creature who identifies herself as the sister of his late father, King Zed. She explains her appearance as the result of practicing "forbidden rituals," and informs Dar that he has a brother, who was raised by evil high priests. The creature predicts the end of the world at his brother's hands, unless Dar kills him before the autumn equinox.
At Arklon's fortress, Lyranna reveals a portal leading to the modern day city of Los Angeles, California, which exists in a parallel dimension. In nearby Long Beach, California, is the Strategic Research and Development Center, which houses the "neutron detonator", a weapon so terrible that its possessor could control the world. Arklon reluctantly agrees to Lyranna's offer to secure the detonator in exchange for becoming his queen.
In Los Angeles, Jackie Trent (Kari Wuhrer), the spoiled teenage daughter of United States Senator Herbert Trent, drives recklessly through the streets with two police cars in pursuit. Attempting to evade the officers, Jackie enters an alley, and all three cars pass through the portal to Arklon's fortress. Soldiers surround the two policemen, who assume they have stumbled into a science fiction convention. When the soldiers set fire to the police cars, the officers jump back through the portal and escape, while Jackie speeds away from the fortress. Hours later, her car runs out of fuel and she searches the wilderness for a gasoline station in the vast desert. After camping for the night, she is awakened by Dar and his animals. Jackie assumes Dar is a circus performer and joins him on his quest, hoping he can lead her back to the city.
The next day, Arklon's soldiers kidnap Jackie and return her to the fortress. Arklon, who now hides his scarred face behind a partial leather mask, explains Jackie's presence in the parallel dimension, and promises to return her to Los Angeles if she assists him in acquiring the neutron detonator. Although Jackie knows nothing of the weapon, she falsely claims that her father can accommodate the warlord.
Dar makes his way to the fortress and passes through the portal in pursuit of Jackie, Arklon, and Lyranna. The warlord notices the letter "A" embossed in the palm of Dar's right hand, indicating they are brothers. He ruptures a gas pipe, trapping Dar behind a wall of flames while Jackie guides the two villains through the city. Dar is hospitalized after police subdue him with a Taser, and his tiger is placed in a zoo.
On the street, Jackie tells Arklon and Lyranna that their strange attire is drawing unwanted attention, and convinces them to shop for new clothes. When she flees her captors, the enraged Arklon wrecks the clothing store, and police release a composite sketch of the perpetrator.
The next day at a police station, Detectives Coberly (James Avery) and Bendowski (Robert Fieldsteel)) question Dar about wanting to know who he is and where he comes from, but Dar refuses to talk. When Dar sees the wanted police sketch of Arklon, he manages to grab his sword and escapes through a window to continue his quest. Jackie happens by and drives Dar hide out in her Beverly Hills home.
Meanwhile, Arklon steals the uniform of a drunken military officer and gains access to the Strategic Research and Development Center, where he is joined by Lyranna. Dar and Jackie see the uniformed warlord on a television newscast and follow him to Long Beach.
Arklon and Lyranna break into the facility and steal the weapon, unaware that they have triggered its detonation timer. Using his mind reading skills, Arklon learns of Lyranna's plot to kill him and usurp his throne, so he abandons her in Long Beach and speeds back toward the portal in a stolen jeep. Jackie and Dar give chase, accompanied by Lyranna, who offers to help defeat the warlord. Upon reaching the portal, Lyranna agrees to apprise Senator Trent of the situation, motivated by her lust for powerful men.
Arklon evades capture and makes his way to the zoo. Dar and Jackie follow, guided by Sharak. The warlord shoots the eagle out of the sky with the Key of Magog, then creates a flaming crevice in the ground. Ruh, the tiger, breaks free from his cage and assists the ferrets in relieving Arklon of the detonator and the key.
The brothers engage in a sword-fight, which ends with Arklon falling into the flames, declaring "The world is mine!" While Dar attends to his wounded eagle, police escort Admiral Binns to the site, and he disarms the bomb with only a second to spare. When Dar and Jackie return to the portal, he bestows his ferrets on her and promises to return, now that he has possession of the key.
Back in his own world, Dar encounters a group of pilgrims who gather to worship Jackie's abandoned car, and dance to music from its stereo system.
