Stingray Season 1 Episode 37 Hostages of the Deep

When Troy meets the orphaned son of an ex-WASP aquanaut, he decides to give the boy a Christmas to remember. He arranges for the young lad to join the Stingray crew in a re-enactment of a battle with a mysterious enemy craft, which was left abandoned after the original conflict. However, Troy is unaware that a member of the crew is still aboard the vessel - and when Phones boards the ship to take command, he is captured and forced to lure Troy into a trap.