a small town overrun by a strange madness. Miners unearth ancient
parasites, in the shape of worms, that attack the brains of their hosts,
entering through the nose or ears. While the infected townsfolk lose
all their inhibitions, Howie must save his sister Sheila, the only
person who truly cares for him. Deprived of Sheila's guidance for the
first time in his life, Howie struggles to evade his maddened neighbors
and destroy the parasites. Some of the infected break into the sibling's
home and infect Sheila, but Howie's infection fails, the parasite
leaving his body only moments later.
Howie experiments with his former parasite in a jar. Its form
reminding him of a slug, he tries to kill it with salt, but it only
revives it. Instead, sunlight through a nearby window then bathes the
jar with light and kills it. At their home, Howie ties up Sheila outside
until daylight. Sheila is exposed to sunlight and her parasite flees
her body, returning her to normal. She reassures her brother that the
hurtful things she had said to him was the work of the parasite; she
would never willingly say such things. Sheila realizes that due to his
mental illness, he lacks what the parasites need in a host and so are
not able to infect him.
After Sheila finds out about how Howie's parasite revived, she
concludes that the parasites must have their hosts eat large quantities
of salt in order to survive, which leads them to investigate the local
salt mines for the possibility that that is where they are during the
day.
Sheila is eventually re-infected. At first he is unsure whether it's
her or not, until her frustrated parasite screams insults at him. Howie
and Sheila's father had taught him how to safely set up dynamite, which
he does at the entrance of the mine.
He waits until just before sunrise, when all the infected are headed
to the mine to escape the daylight. Just before they reach the darkness
of the mine, Howie detonates the explosives, blocking the entrance. With
seconds until sunrise and the mine blocked, the parasites are
completely exposed with nowhere to go. The parasites flee their hosts,
leaving them unharmed, to die on the ground. The three original miners
that became carriers and distributors of the parasites unfortunately die
from the multiple exit wounds the many escaping parasites create. In
the end Howie is thanked as a hero, his "weak" brain having been the
strength that saved him and his neighbors.
