While staying with his elderly aunt Kathryn, Evan Ross accidentally finds himself in a strange and eerie place – an old toy store. On its shelves, he discovers a tin can that, according to its label, contains Monster Blood. The strange, sticky substance really does look like the blood of some bizarre creature. But even stranger is how this slimy mass keeps growing – first overflowing its can, then a bathtub, then an entire garbage bin. Evan worries that this tendency to grow is nothing less than the expression of a monstrous appetite…