Lost in the African jungles for over a year, Dr. Charles Decker (Michael Gough, Horror Hospital) has returned to England with Konga, a baby chimpanzee. Disappearing into his lab, the mad botanist begins work on what he believes will be his greatest achievement. Having witnessed a Baganda witchdoctors use of a rare carnivorous plant to produce accelerated animal growth, Decker injects Konga with the same serum. Using the gorilla-sized chimp to brutally murder his enemies, Decker himself soon becomes victimto Kongas uncontrollable rage. Grabbing the scientist, the berserk chimp -- whos grown to monstrous size -- breaks out of the lab and rampages through London, a city whose salvation rests with the military, whos been ordered to destroy Konga at all costs.