The 21st century world is a radioactive wasteland as a result of a nuclear war. A travelling scavenger comes across the remains of a cyborg named Mark 13 in the desert, and salvages pieces of it. The cyborg head ends up with a metal sculptress, who is unaware of the cyborg's infamy as a governmental killing machine project that was scrapped due to its defects. Mark 13 reconstructs itself utilizing household appliances and metal parts, and goes amok.

M.A.R.K. 13 is a prototype killer combat droid. Its name is a reference to the Gospel of Mark in the New Testament of the Bible, part of which reads "no flesh shall be spared".

The robot, capable of reconstructing itself if damaged in combat, can augment and rebuild its body using any machinery and metal parts available nearby. It also comes equipped with an anti-personnel chemical weapon in the form of an injectable cytotoxin that causes sensory distortion (hallucination) before death. The ultimate purpose of this weapon is to allow the government to commit mass genocide of its own citizens to alleviate overpopulation.

M.A.R.K. 13's Achilles' heel is a faulty insulation system, highly sensitive to moisture and humidity. Although built for fighting in arid terrain, this huge flaw in the droid caused its governmental project funding to be initially suspended. At the end of the film it is revealed the Mark 13 will enter mass production.[1]