Grayhawk Research was developing a new kind of animal growth hormones dubbed GH-1-66. But when GH-1-66 had unusual side effects it was disapproved for use by the FDA and orders him to be disposed of. So Anton Grayhawk illegally dumped in the swamp where it starts leaking. Now the side effect is anything that consumes the growth hormone grows and anything that eats the animal or insect that eats the growth hormone grows. The flies drink the leaking liquid and are consumed by the swamp frogs and toads. Now the town of Moorsville is being over run by over sized frogs.
This is a remake of the 1970s’ classic crap shack, but has nothing to do with that movie. Neither in plot nor in characters, I feel that it has been changed enough that asking permission by the people who own the rights of the original copyright is not needed. But see for yourself.