Season 18 - Episode Guide

Mark and Lisa must help their Uncle George prevent an ancient and mysterious box - the doorway into a dark and menacing world - from ever being opened.

George and the twins begin the search for the keys to the Box of Destiny.

When Lisa and Mark go in search of the second key, they are followed by the Watchers, who have been ordered to kidnap them.

Deep underground lies a mysterious box, left on earth by the rulers of Heritron, who plan to use it to enslave the human race. Mark and Lisa find the second key. The Watchers try to kidnap the children, but they are saved by George, and their own quick wits. They locate the third key at the Roman baths.

George and the children persuade Professor Waters to take them to the Box.

George breaks into the Janus Foundation to get to the Box. But all the children are captured when they attempt to rescue him from a trap.

The doorway to Heritron is opened, though when George and the children escape from the Janus foundation they are betrayed by Erica, who is revealed as a watcher.

Professor Waters gets the Box back from the Watchers. George goes through to lock the doorway into Heritron, but the Catchers are waiting for him.

George is held captive, and Anna tells the children they must rescue him.

Lisa and Mark find George trapped in a crystal cell. They manage to set him free, but can they escape from Heritron?