One evening, Petrie begins telling a tale of the best creatures of the world, the Flyers, but it is met with disapproval from Cera. Meanwhile, a herd of dinosaurs visits the Great Valley. Later that night, Littlefoot sees a strange blue-colored meteor falling from the sky and crashing into Threehorn Peak, a volcano in the Smoking Mountain range. When Littlefoot describes it the next morning, the adults in the Great Valley do not believe him except for two newcomers, the mysterious "Rainbow Faces", who speak about possibilities of wonders beyond what they know . The Rainbow Faces suggest the rock may be a "Stone of Cold Fire", a stone possessing magical properties.
Pterano, the outcast uncle of Littlefoot's friend Petrie, overhears the conversation and conspires to use the rock to take control of the Valley. Pterano asks Petrie, who idolizes him, for the location of the rock and learns its location. Littlefoot's friend Ducky overhears Pterano's plan, but Pterano and his cronies, Sierra and Rinkus, abduct her before she can warn the others, and set out to find the Stone. After discovering Ducky's kidnapping, the adults tell the young ones how Pterano led some of their herd during their search for the Valley, but had accidentally led his followers to a pack of Sharpteeth. Pterano was able to fly away, but the event left him emotionally scarred. He was expelled from the herd as punishment for leading his followers to their deaths.
Because the adults are slow to reach a decision, Littlefoot, Petrie, Cera, and Spike take off by themselves in search of Ducky. Meanwhile, Ducky escapes and falls into a cave while fleeing. After the children find her, Ducky comforts Petrie, who is distraught about his uncle's actions, by stating that Pterano is the least wicked of the three Flyers, and that he still has a potential of doing good. Meanwhile, Sierra displays mutinous feelings towards Pterano, and Rinkus convinces him to betray Pterano once they find the Stone.
The children pursue the Flyers, hoping to reach the Stone before them. Aided by the Rainbow Faces, who suddenly appear and offer their knowledge of volcanoes, they manage to arrive at Threehorn Peak before the Flyers. However, both groups discover that the Stone is just an ordinary meteorite. Lamenting over this realization, Pterano explains that he had meant to create a paradise with the power of the stone, not realizing that this paradise already exists in the form of the Great Valley. Unwilling to believe the Stone is not magical, Sierra and Rinkus betray Pterano. However, as they attempt to get the Stone to give them power, the volcano begins to erupt, and Pterano saves Ducky when she falls off the mountain.
Petrie's mother arrives with a friend to evacuate the children, leaving Sierra and Rinkus to be caught in the Stone's explosion. Pterano is thanked for saving Ducky, but as punishment for his plan, he is exiled from the Valley for five years, which he accepts. That night, Littlefoot finds the Rainbow Faces and asks them if the meteorite he saw really was a Stone of Cold Fire. They admit that while it wasn't, his effort to search for it was what really mattered, and reiterate that there are many unknowns to be discovered "beyond the Mysterious Beyond". Littlefoot is then momentarily distracted, and when he turns around, he finds that the Rainbow Faces have disappeared in a pillar of light. As his friends find him, an inspired Littlefoot reflects that there are many unknowns and that such unknowns make life wonderful.Thomas Dekker as Littlefoot
Anndi McAfee as Cera
Aria Curzon as Ducky
Jeff Bennett as Petrie / Spokes Dinosaur
Michael York as Pterano
Rob Paulsen as Rinkus/ Spike
Jim Cummings as Sierra
Kenneth Mars as Grandpa Longneck
Miriam Flynn as Grandma Longneck
John Ingle as Cera's father
Tress MacNeille as Ducky's Mom / Petrie's Mom
Charles Kimbrough as Rainbow Face #1
Patti Deutsch as Rainbow Face #2
The songs are written by Michele Brourman and Amanda McBroom."Beyond the Mysterious Beyond" - Littlefoot, Cera and Rainbow Faces (Thomas Dekker, Anndi McAfee, Charles Kimbrough, and B. J. Ward)
"Good Inside" - Littlefoot, Cera, Ducky, Petrie and Spike (Thomas Dekker, Anndi McAfee, Aria Noelle Curzon, Jeff Bennett and Rob Paulsen)
"Very Important Creature" - Pterano, Sierra and Rinkus (Michael York, Jim Cummings and Rob Paulsen)
"If We Hold on Together" (instrumental)
Production of the film had concluded by June 2000. This is the first film in the series to use Digital ink and paint rather than traditional cel animation that was used in the first 6 films.December 5, 2000 (VHS and DVD)
December 4, 2001 (VHS and DVD)
December 2, 2003 (VHS and DVD - 4 Movie Dino Pack (Volume 2) and 9 Movie Dino Pack)
November 29, 2005 (DVD - 2 Mysteries Beyond the Great Valley)
Entertainment Weekly gave the film a "B" and wrote that it "beats the heck out of Barney's infantile dinosaur tales," with its "velociraptor-fast pace and a minimum of treacle". In August 2014, the New York Post ranked each of the 13 Land Before Time films released up to that point and placed The Stone of Cold Fire at number 10, writing, "Though not quite as annoying as 'Tinysauruses,' the name 'Rainbow Faces' comes pretty close."