Olivia is sure that the people moving to 16 Olcott are hiding something. The last family moved out late at night, and the new tenants, the Donahues, have no idea why. Just as Olivia manages to befriend Janey Donahue, she witnesses strange events. And it all starts with a mysterious letter from the Sentinel, who claims: if the Donahue family “does not stop the invasion” and does not leave the house, the rooms will soon smell of death...