The UFO's wreckage is too deep for Skydiver One to retrieve and a Royal Navy admiral, Sheringham, refuses to divulge any information on the incident or the ship's mission.
Straker decides to see if he can get information out of the Admiral's secretary, astronomer Sarah Bonsanquet (the daughter of one of the astronauts who disappeared while building the SHADO Moonbase).
Straker learns that the ship was going to dump nerve gas into the sea but the aliens see an opportunity to release it into the atmosphere to kill the Earth's human population.
He adds that "Destruction" is perhaps the "dullest" episode of the series, remarking that the UFO assault on the navy vessel "goes on and on, seemingly endlessly, with not a single member of the primary cast involved in the events to make it meaningful or vital.
It describes "Destruction" as "the most engaging of the 'procedural' episodes of UFO, where the script isn't so concerned with overt action, but instead boardroom politics, diplomatic negotiations and red tape".