Identical ten-year-old twins Kim and Tim are no longer the darlings of the Willem family. That changed when the new baby, Abby, arrived. The twins resent Abby and make up their minds to become difficult. So when weird things begin happening, their parents don't believe them when they talk about the large, old-fashioned black car that glides by with no driver; the small, grey dog with the golden, glowing eyes watching from the hedges; and the gnome-like intruder in the basement, who disappears behind the furnace when followed.
The situation becomes even more interesting when Kim and Tim meet the new special education instructor, Mr. Harrison Heed; the two children soon discover that he's much more than a teacher at their school. Then, something unnatural occurs; baby Abby is abducted by thieving creatures called hdodas.