When Angus McCawtup High School is threatened with closure due to earthquake damage, two pupils come up with a bizarre idea that they present to the headmaster. For Professor Russell Sprout the thought of losing his beloved school and having to spend time with his wacky wife was all too much. As far as he was concerned, any idea was a good idea. The boys put it to the professor that they return to Umbadinga to look for precious stones to raise money for earthquake repairs. Reluctantly, Professor Sprout agreed, but he made one condition, that Miss Van Hyre and Mr Fields go with them as responsible adults. Now there's an oxymoron if ever there was one! Can they get back through the subterranean portal, especially as they don't know how they got through in the first place? What could possibly go wrong? You'll have to join the adventure and find out first hand...if you dare!

When an end-of-term field trip goes horribly wrong and not all the students return, the teacher loses the plot. One student hatches a plan and together with the school bus driver, they attempt their own rescue mission. The lost children enter a new world through a subterranean portal and things take a twist when the group get split up. Umbadinga is full of mystery and intrigue. Their pursuit for self-preservation leads them into encounters with weird and wonderful creatures, but not all of them are friendly. Become part of the adventure in Umbadinga, be a fly on the wall during the battle and mind-boggling escapes. But the big problem is, can they get back home again? That's for you to find out!