This is a bit talkie but overall it fulfills the Cold War fear of radiation and its implications. The monster here seems determined to destroy. Animals, generally have two things on their minds, food and reproduction. This big lizard apparently has a third thing: it enjoys rampaging. Why it feels the need to crush cars and chase people down the street seems to imply motivations that are more punitive. It also seems to have the ability to disperse radiation when it wants to, frying people who confront it. The film is strongest in the action leading to the discovery of the creature. The science is valid and interesting. Some say it's a rip off of "The Best from 20,000 Fathoms." I guess in many ways it is, but it has a good story to tell and leaves us guessing at the end.
Review of The Giant Behemoth
