A Naval vessel shoots down a UFO in the Atlantic, but the Admiralty rejects further investigation into the incident. Straker suspects a cover up and wants to know why, so Foster courts Admiral Sheringham's secretary, Sarah Bosanquet. What they discover could mean the end of all life on Earth...

A UFO imbues three young people with incredible powers. One blows up a radar station, a second steals fingerprints and tries to get aboard a Skydiver sub, blowing it up. The third, a woman, tries to blow up SHADO HQ but the UFO that is feeding her power has now been destroyed.