Your favorite exploitation / grind house type film.
The plot involves Sardu and his little assistant Ralphus bringing a Theatre of the Macabre to life. Using real people on stage, Sardu's act consists of torturing these poor unfortunate souls to death in front of a paying audience. That's just what's shown to the customers. The real torture is backstage.
There are scenes included that feature a human dart board, living furniture, dentistry, and odd uses of straws. This film is the apex of horror exploitation.
"My mother taught me. I used the whole chicken. The secret is cooking it alive."