The Plants find half of a treasure map and a photograph in Dave’s basement. They discover various clues that lead them to search for a mysterious treasure in the legendary Dragon Bone Town.

While they are there, the Plants find the dinosaur egg that Dave’s father left behind. When they board the ghost train, they encounter space-time turbulence and end up travelling to another world. After surviving the attack from Sigilmassasaurus, the Plants enter the treasure site after solving the puzzles on the Pentaceratops tablet. However, they are left disappointed when they open the treasure box. At this time, disaster strikes.

What is the mysterious treasure? Can the Plants save themselves from danger? Join the Plants in their treasure hunt in the secret realm!