|Information in this article is non-canon|
This comes after The Land Before Time XVI: The Threehorn Gathering and before The Land Before Time XVIII: Hunter Valley.
In this one, Littlefoot hears of a mystical Fire Stone (lava rock) under the Great Valley that will supposedly give great knowledge and understanding. Having felt that the grownups will never take him too seriously, he starts to covet this rock.
Eventually, he hangs out wiht the wrong sort of friends, and comes to snub Cera, Ducky, Petrie, and Spike. He becomes more and more obsessed with the Fire Stone and eventually completely snubs his old friends, feeling that they are not cool enough like his new friends.
However, he soon comes to realize that his new friends are not what they seem and learns the value of true friends and the dangers of greed.