A young woman encounters a malevolent supernatural force while searching for her missing sister in Tokyo, a mean high school prank goes horribly wrong, and strange things begin happening in a Chicago apartment building.

When social worker Rika is sent to check on a traumatized old lady whose family have moved in at the site of the notorious Saeki family murder case, she unwittingly unleashes a cycle of terror that is transmitted via its victims further and further from its original source.