A girl is arrested after trespassing on the land surrounding the huge medical centre where she is kept captive under maximum security. Mark and Song Li learn that the girl is an extra-terrestrial who wants to return home. Her ship lost fuel during their journey through space, and they landed on Earth to collect their fuel, which is water. They wanted to land in the ocean, but they accidentally landed near the medical centre. The girl (Lex) wants to go back to the ship to go back to her home town. So Mark and Song Li try to help her escape. (thetvdb.com)