'Suddenly it was as though Cass and Carl had dissolved into the wide trunk and were sliding effortlessly down, down, inside the tree.'
So the twins entered the mysterious world of the Trumpalar. Their adventures had begun when they set out to save the Tumper Tree from destruction. These adventures were to take them into a past world of convicts, soldiers and buried treasure, and there were many dangers for them to overcome if the magical tree was to survive.