Swendler (Denis Goacher) had planned on defying Ziebrecken (Aubrey Morris) and was going to put both Mark (Gerald Flood) and Peter (Stewart Guidotti) ashore on a deserted island instead of killing them.  When the underwater missile explodes Swendler finds out that it was sabotaged by the two prisoners.  Instead of killing them or freeing them Swendler returns to Aegiria and tells Ziebrecken what happened.

Meanwhile the Royal Navy, under Captain Payne’s (Peter Williams) command, hears the explosion of the missile.  Using monitors all over the Pacific, they triangulate where the explosion came from and send ships to the area.

Ziebrecken is not happy about the missile explosion, the fact the Mark and Peter are still alive or the fact that Westfield (Hayden Jones) and Ann (Caroline Blakiston) tried to defy him and send out a message of their own.  He is happy that the other missiles are in place, ready to launch and that the radio system is completed.  He sends out a message to the world stating that he will use the nuclear missiles if they don’t surrender to him and obey his orders.  He gives the world three hours to comply.

Ziebrecken then orders Swendler to kill Mark, Peter, Westfield and Ann.  Swendler, not having the stomach to randomly murder people, refuses.  Ziebrecken tells a couple of his minions to take everyone away, including Swendler, and kill them.  The condemned need to do some quick thinking, not only to save their own lives, but to stop Ziebrecken from launching the nuclear missiles.  What no one counted on was the weather.

There is a plainness about “City Beneath the Sea” that wasn’t there in the Pathfinder series.  Perhaps it was the variety of characters or their personalities.  The Pathfinder series also had exotic locations and a lot of cliffhangers.  Even the bad guy in the Pathfinder films had, what seemed to be the occasional moment of empathy. 

The underwater scenes in “City” were done dry for wet.  I’m not sure what special effect the used create the feeling but at times it was difficult to see what was going on.  “City” also included some scientific facts along with the story to make it a little on the educational side.