Lost is the fourth episode of the first season of Prehistoric Island. It runs 13 minutes and 25 seconds.
The episode starts out in the plains where the herbivores are feasting. As they graze, Dylan and Daisy watch them, and they play nearby. As they play around, they see a Therezinosaurus. The dinosaur looks so peculiar to them, and they decide to walk away from it.
As they walk away, huge herds of herbivores have spread out through the plains to make way for a Diplodocus. As the young Dilophosauruses walk around, the two teenage Allosauruses from two episodes ago appear, and they plan to chase the herd, while their parents choose their victim. The young Allosauruses carry out their plan, causing a stampede among the herbivores.
As the hunt goes on, Dylan and Daisy are caught in the middle of the stampede. The siblings try to stay together, with Dylan hiding under a Brachiosaurus, while Daisy manages to escape.
Daisy waits for him, but sees the herd still stampeding. She attempts to call for him, but once again, no response. She has no choice but to look for her brother.
Meanwhile, Theo is fighting another Triceratops for his territory, while Todd watches nearby. As he watches, Malachite watches from behind. With Theo distracted, Malachite attacks Todd. Todd gets up, and charges at Malachite like his father, only for Malachite to bite his eye. However, Theo, who has just won the battle, defends Todd and scares away Malachite once again. However, Malachite has blinded his left eye while attacking him. Daisy, who sees this all, decides to leave.
Late in the afternoon, Daisy decides to have a drink. At the other side of the lake, a Sauropelta drinks from the lake. Upon seeing Daisy, it roars aggressively, forcing her to retreat once again.
As she walks deeper into the forest, she hears a familiar noise fill her ears. She follows the source, and finally finds Dylan. The two siblings reunite and greet each other, though Dylan has obtained a wound in his leg. The two young Dilophosauruses run off and they play once again. But a change is coming to the island, and it is the arrival of the dry season.