A treacherous lawyer, a representative of the bank, threatens to seize the house and possessions of Myrna’s grandmother for debts. By chance, her restless grandchildren find out about this... They must help their grandmother! One of the kobolds reveals a secret to the children: somewhere in these lands the treasures of the O'Connor family are hidden... Having found an ancient letter with the key to the cache, the brave twins, together with their friends, set off in search of the treasure. But to find him, they have to overcome many obstacles...