Mystery writer Cornelia Van Gorder has rented a country house called "The Oaks", which not long ago was the scene of some murders committed by a strange and violent criminal known as "The Bat". Meanwhile, the house's owner, bank president John Fleming, has recently embezzled one million dollars in securities and has hidden the proceeds in the house, but is killed before he can retrieve it.
The head of a major cosmetics company experiments on herself with a youth formula made from royal jelly extracted from wasps, but the formula's side effects have deadly consequences.
A backwoods game warden and a local doctor discover that giant leeches are responsible for disappearances and deaths in a local swamp, but the local police don't believe them.
Frederick Loren invites five strangers to the party of a lifetime and offers each of them $10,000 if they can stay the night in the reportedly haunted house. Armed with a gun for protection, each guest arrives in a hearse and will either leave in it much richer…Or dead.