Alison and Robert visit a prison after a series of mysterious suicides take place behind bars. There they encounter a serial killer, who blames a malevolent spirit called the Rat Man on his own murderous spree. As Alison strives to banish the evil from the place to help the other convicts, she puts herself in terrible danger.

Alison visits a woman who starts exhibiting symptoms of the disease that her fiance's first wife was killed by, and realises that she is possessed by the dead woman's spirit. Meanwhile, Robert's sudden scepticism baffles Alison, who is unaware of his fatal illness.