TV Guide panned the film stating, "Although this premise is ripe with comedic opportunities, the production is hampered by classically inept film-making, and the story unfolds so slowly one begins to think the film is running in reverse. The acting is even worse. Still, horror fanatics might find some interest in Rick Baker's lizard makeup". Oh the Horror! gave the film a negative review calling it "embarrassing" and called the ending "ridiculous", panning the film's execution, dialogue, and script. Mineralogist Paul Carlson is struck by a lunar meteorite while observing a meteor shower. Lodged in his brain, the meteorite causes him to transform into a strong and vicious lizard (the titular "moon beast") whenever the moon comes out. In his lizard form, Paul loses all traces of his human self and goes about killing people at random. While human, Paul is subject to spells of dizziness and nausea, causing his girlfriend Kathy Nolan and friend and former teacher Johnny Longbow to become concerned. Eventually it is shown that Paul is the monster, and deduced that the meteorite fragment in his brain is the cause of his transformations. Plans are made to remove it from his skull, but the NASA brain surgeons realize, after another X-ray and Johnny remembering some Native American legends documenting similar phenomena, that the meteorite has disintegrated and will eventually cause Paul to self-combust. When Paul learns of this, he escapes into the desert, presumably to kill himself so he will not cause any more harm. Kathy, Johnny, and the local law enforcement follow him, and Johnny shoots him with an arrow made of the original meteorite, which causes him to explode.