This song has been on my mind for a while lately. Not so much the meaning, but the tune. Very catchy… The music video for it (linked above) makes it even better. VERY VERY cool stuff. As far as the song goes… I think it is about how they built up to what they thought they wanted (windmill/tower on on island), which turned out to not be at all what they expected (a prison), and now they feel trapped in a sense by their own doings (deep voice, satanic/evil, laughing, captain leading the way).