Four employees of Island Fisheries come to a sun-scorched, isolated island to negotiate fishing rights with the sullen, paranoid islanders who have good reason to be afraid. Soon after the arrival of the four, a mysterious force the islanders thought was chained forever in the dark basement of the foreboding old Counting House is once again on the loose, savagely killing its women. Caught in a power struggle between rival island factions over how to stop the killing, the mainlanders are jailed. They manage to break out, but with a vigilante mob on their heels, can they reach the boat in time? They do, only to confront the mysterious, terrifying force.

A group of friends are plagued by recurring nightmares set in the Middle Ages. In an attempt to bring peace to their nights, they decide to undergo a psychic seance. They soon find themselves in an unlikely Middle Ages, battling a swarm of accidentally released killer horseflies. To defeat the pesky insects, they must find and smoke the dried leaves of a magical herb.

A group of friends on vacation are attacked by a swarm of killer horseflies. The situation worsens because the flies are attracted to blood and attack their victims, causing them to implode or cause serious injury to feed. The friends must use large amounts of cannabis to repel the insects, discovering that the THC in marijuana is the only substance capable of stopping their rampage.