Space aliens led by an entity which takes the form of a deceased WW2 officer acquaintance of Nelson's invade the Seaview, intending to reactivate an underwater atomic base to acquire its energy.
Did You Know?
Admiral Nelson shows that the alien impersonating Garrity is a fraud by stating that he went missing in action 23 years ago in WW II. The error is that while this interval would have been correct from the time the show was filmed in the mid 1960s, it would have been way off for the time-frame the show is set in, sometime in the mid 1970s. See more