Children's drama series about a group of Scottish schoolchildren who travel to Australia in search of UFOs. Trapped under Ed's house, the group are saved by a call from Stanich to the agents. Harry is susicious that there is a traitor in the midst of the group, and when Chrissie infiltrates a local military camp she discovers chilling new information. The group decide that the twins hold the key to what happened on the ridge and they set off to meet the spooky duo at the coast.