A scientist, Gilbert McKenna has an accident where he is exposed to high levels of radiation. Surprisingly this does not kill him but instead leaves him unable to be exposed to sunlight. Whenever exposed to sunlight, McKenna devolves into a lizard man with homicidal tendencies. After having a brief fling with a nightclub singer, and killing her boyfriend, McKenna is on the lam from the police which culminates in a one on one battle on top of a tower. Great monster costume and Shatner type acting from Clarke are the most memorable parts of this great 1950s creature feature.