I remember a film vividly when I was a kid. It was a dystopian science fiction film from the 1990ís. The protagonist is brainwashed. There are these alien creatures that kind of look like swamp thing, the hero is some kind of servant to the aliens, he betrays one of them, the aliens bath in some kind of liquid, that the hero throws a device into which immediately changes the bathing liquid into a solid, then he hitís the alien in the head, assassinating it. Later, we find out the hero has been brainwashed previously and is being brainwashed again. Please, someone, help me with this title.