Kevin and Annie find an abandoned dinosaur egg. Once the egg hatches, Annie names the dinosaur Tasha.
Tom believes other people might be in the Land of the Lost and discovers Christa, the jungle girl. She helps find an antidote to save Tom after a poisonous lizard bites him.
The Porter family goes searching with Tasha to find a way home. Unfortunately, they run into creatures called Sleestak and their leader, Shung. The Sleestak steals the family car and captures Tasha.
The alignment of the three moons causes the Land of the Lost inhabitants to act strangely, including Stink and Tasha. They Stampede towards the Valley of Death. Meanwhile, Christa and the Porters race to save their friends from death.
Annie finds Shung’s magic crystal sword, which gives her powers she never dreamed of. However, its evil nature slowly changes her for the worse, and she begins acting like Shung.
Annie’s pet dinosaur, Tasha, gets in trouble once too often, so Tom decides she should be returned to the jungle to fend for herself.
A Knight named Sir Balen finds his way in through a portal into the Land of the Lost.
A volcano erupts, and lava is moving straight for the Porters treehouse.
Shung finds one of Christa's keepsakes and uses it to establish a hypnotic mind control over her.
A series of earthquakes convinces Tom a new dimensional gate will soon materialize, so the Porters head out to find it.
Tom and Kevin encounter Sleestak when they venture to the distant lake to find water.
Kevin is convinced that Stink is the culprit when objects start disappearing from the tree house.
When the last of the Porter’s batteries stop working, Tom sets out to find a replacement energy source and enter into Sleestak territory.