Before we are introduced to any of the characters, the central problem is made clear. A Nazi propaganda station is broadcasting as "The Voice of Terror", crowing over recent military successes and making stark threats about sabotage attacks which have either happened or are just happening as the broadcast takes place. As the radio transmission plays out, we are shown some of these terrible events. In one sequence, for instance, we are informed that "an important diplomat boarded a train at a little station outside Liverpool", followed by shots of the signal levers being worked by seemingly ghostly means, leading to the rails being divided and a catastrophic crash, with the train hurtling off the tracks and down a ravine. Throughout the broadcast the phrase "This is the Voice of Terror" is repeated in ominous fashion.
I couldn't help wondering if this fictionalised version of Nazi propaganda broadcasts might have been the direct inspiration for the alien threats at the start of each episode (or sometimes after a lengthy "cold open") of Captain Scarlet and the Mysterons - see here, for instance, at around 6.15 minutes:
Tonally, they are very similar, and of course the Mysterons often went about their acts of alien sabotage by ghostly means, making levers work by themselves, etc. There is also the matter of Captain Scarlet's Mysteron-induced invulnerability, making him ageless, invincible and unchanging. Elementary, one might almost say.