A scientist experimenting with speeding up human evolution hires an uneducated, but bright, Gwyllim from the nearby Welsh mining town. He proves a devoted lab assistant, but not content to stick to animal subjects, Gwyllim speeds up his own evolution, becoming a super genius with 6 fingers and a huge cranium. With such mental powers, does the rebellious former coal miner acquire equivalent wisdom and maturity, too ?
—David Stevens