Little Bear's Adventures of The Land Before Time IV: Journey Through the Mists is an upcoming Little Bear/Universal crossover to be made by Hiatt Grey. And is the sequel to Little Bear's Adventures of The Land Before Time III: The Time of the Great Giving.
Littlefoot notices a Longneck herd entering the Great Valley and informs his grandparents, who tell him that the Longnecks are their cousins and that they must go and greet them. Upon the herd's arrival, the Old One, the herd's leader, tells the Great Valley's residents that her herd has been migratory ever since a heavy period of rain turned their old home into a marshland called "The Land of Mists" and became the home of many dangerous creatures. Later, Littlefoot meets a female Longneck named Ali and invites her to play. He introduces her to his friends, but as she is not used to associating with diverse species, she is afraid of them.
Meanwhile, Grandpa falls severely ill. The Old One notes that the illness is lethal and that no dinosaurs recover from it unless they eat the petals of the "Night Flower", a flower which can only be found in the Land of Mists. Though Littlefoot is warned that the Land of Mists is too dangerous, he becomes determined to save his grandfather and asks Ali to take him there. She agrees on the condition that Cera, Ducky, Petrie, and Spike don't come, claiming that they will slow them down. As the two of them make their way, they pass through a cave and a sudden earthshake causes various stalagmites and stalactites to come crashing down, separating them. Ali decides to return to the Valley and convince the others to help her free Littlefoot. Meanwhile, Littlefoot tries to find a way out and meets an old Archelon named Archie, who offers to help him dig through the rocks.
As they work, Littlefoot and Archie are interrupted by a Ichthyornis named Ichy and a sightless Deinosuchus named Dil, who intend to eat them. Ichy and Dil pursue Littlefoot and Archie, but are knocked out when Ali and Littlefoot's friends dig a hole in the rock wall and send rocks tumbling down on them. Archie shows them a way to the Land of Mists and reminds them to stay close together before departing. In the Land of Mists, Cera is separated from the group. The others meet a mouse that Ducky names Tickles after his fur, and Tickles help them find Cera. However, Cera falls into a river and is pursued by Ichy and Dil. Ali saves Cera and distracts the predators, after which Cera softens towards Ali. Later, Ali explains her prejudicial behavior, but remarks that her attitudes towards Littlefoot's friends has now changed.
When the seven stop for the night, they realize they are in a field of Night Flowers after they bloom, and quickly stock up on them. As they make their way home, Ichy and Dil return for another attack. During the chase, Ducky falls into a river while retrieving a Night Flower, and Spike speaks for the first time by calling out her name. As Petrie rescues her from the predators, Ichy and Dil get into an argument when Dil mistakes Ichy for Ducky and tries to eat him. When they dismiss each other, Dil flings Ichy off with her tail, but is pursued by a Hydrotherosaurus shortly after. Meanwhile, the children say goodbye to Tickles and head home. They give Grandpa the blossoms, and he gets better upon eating them. Ali then leaves with her herd, but not before trying to convince Spike to say goodbye, which he does not, as he is too interested in consuming leaves. The narrator concludes that Littlefoot and the others will indeed meet Ali again one day.
- Team Griffin/Eeveelution, The Griffin Family, Vinny Griffin, Glenn Quagmire, Cleveland Brown, Joe Swanson, Doug Funnie, Skeeter Valentine, Roger Smith, Bender Bending Rodríguez, Minerva Mink, Master Shake, Meatwad, Frylock, Pazu, Sheeta, The Crystal Prep Girls, Wubbzy, Widget, Walden, Daizy, Natsu Dragneel, Lucy Heartfilia, Gray Fullbuster, Erza Scarlet, Wendy Marvell, Happy, and Carla guest star in this film.
- The storyline continues in Little Bear's Adventures of The Land Before Time V: The Mysterious Island.