Experimental scientist Andre Delambre attempts to transfer matter through space, using himself as the test subject. But things go horrifically wrong when a common housefly buzzes into the machine, resulting in two grotesque man-fly hybrids. Now, with the head of a fly and a wing in place of one of his arms, Andre desperately hopes that he, his wife Helene and his brother Francois can capture the other mutant - the human-headed, one-armed fly - in hopes of reversing the experiment.