Konga the Monkey

British botanist Charles Decker goes Crazy after he discovers a serum that turns his cuddly chimpanzee subject Konga into a ferocious gorilla-sized ape. To further his hideous experiments, Decker mesmerizes the chimp and sends it to London to kill all his former enemies, including the lover of the woman the doctor wants for himself. This doesn't set well with Margaret, the botanist's assistant and current girlfriend, who attempts to get even by giving Konga an enormous amount of the strange serum and turns him into a Godzilla-sized monster, though she becomes his first victim. Just before going on a deadly rampage, the super-sized ape grabs Decker in one of his enormous hands. His rampage comes to a stop when he and Decker are killed by the British army. Upon his death, he reverts back to a chimpanzee.

Well that's werd