The Claw Monsters was the feature-length version of the 1955 Republic serial Panther Girl of the Kongo. The plot has something to do with mad doctor Arthur Space, who while squirreled away in his darkest-Africa laboratory has developed a serum that can change harmless crayfish into hideous monsters. The Panther Girl, played by Phyllis Coates, inadvertently takes a picture of one of these monstrosities, and things start percolating from then on. Panther Girl of the Kongo was a product of the last dismal days of the serials, meaning that 90 percent of the action highlights were culled from stock footage. In fact, Phyllis Coates is dressed in the same costumes worn by Frances Gifford in Jungle Girl, Kay Aldridge in The Perils of Nyoka and Linda Stirling in The Tiger Woman, allowing Republic to lift stock scenes from all three of those earlier chapter plays.