The film begins with Bill watching the end of The Human Centipede 2 with his accountant, Dwight Butler. Bill receives a threatening prank phone call from an inmate, and punishes him by waterboarding him with three buckets of boiling water. Governor Hughes arrives, ordering Bill and Dwight to put a stop to the violence and promising that they will both be fired otherwise.
Dwight pitches an idea to Bill to fix the prison's problems: suture all of the inmates together mouth-to-anus, forming a giant human centipede, which would be the ultimate deterrent to crime. Bill is skeptical and opposed to the idea, but he has a nightmare about being attacked by inmates and raped by the inmate he castrated. This changes his mind, and he decides to go ahead with Dwight's plan.
Bill and Dwight begin by selecting the inmates who will be part of the centipede. They choose inmates who are considered to be the most dangerous and disruptive. They also select a few inmates who have special skills, such as a doctor and a dentist.
Bill and Dwight then begin the process of stitching the inmates together. The operation is long and complicated, and several inmates die during the procedure. Once the operation is complete, the centipede is placed in a large room in the prison.
Bill and Dwight monitor the centipede closely, and they use a variety of methods to keep the inmates in line. They feed the centipede a diet of liquid food and water, and they use a system of tubes to collect the centipede's waste. They also use a system of cameras to monitor the centipede at all times.
The centipede is initially successful, and it reduces the violence and crime in the prison. However, over time, the inmates begin to deteriorate both physically and mentally. They become increasingly weak and frail, and they begin to develop a variety of health problems.
The film ends with the centipede collapsing in on itself. Bill and Dwight are both killed in the collapse, and the inmates are freed. However, many of the inmates are now too weak and sick to survive on their own.
The Human Centipede 3 is a controversial film that has been criticized for its extreme violence and graphic imagery. However, the film has also been praised for its originality and its willingness to push the boundaries of cinema.
