Things that happen while you're asleep

A few nights ago I went to sleep and, at the beginning of my dream, I was in a large capsule with a number of other people. The capsule was about 50' long, mainly transparent, and travelled through a long tunnel that comprised a series of interesting, entertaining and exciting things for the benefit of the occupants of the capsule as they travelled through the tunnel. Unfortunately, I cannot recall any of the things we saw before the end of the ride.
However, when the ride came to a halt, I was one of the last to disembark and, before myself and another man could get off, the doors closed and the capsule began moving in the opposite direction. We could only watch as the capsule went through the wall at the back end of the 'station' and took us on a long, high-speed ride of terror that ended above ground in another part of the town which neither of us were familiar with.
Managing to climb out of the now stationary capsule, my companion went underneath the capsule and, to my horror, he metamorphosed into a steel strut or support for the rail system that the capsule travelled upon.
Although I managed to avoid a similar fate, I felt that I had fallen from the frying pan and into the fire because the next thing I knew was that I was one of a party of other humans that were now worker slaves to an army of frightening & inhuman creatures that were using us to construct more tunnels.
I remember that many of us were hoping to rebel & overthrow our cruel oppressors, but we were constantly observed & terrorised by the creatures. Eventually there was a form of rebellion, but the leader of the creatures, a tall, muscular, menacing, dark & horned figure escaped, running past me to freedom as it evaded capture.

The last thing I remember before waking up was the dreadful feeling that the danger was not over.