When Cyrus Kriticos dies, he leaves everything behind to his heirs. Cyrus is a very rich man, and after his death he left everything to his nephew and his family, including his home, his wealth, and his evil group of ghosts. The family begins to adapt to its new home, but everything seems strange. Perhaps this house will be haunted. There is a strange turn of the walls, and there are powerful and repulsive entities that threaten to exterminate anyone on their way in and out of that house, which is frightening everywhere.
There isn't enough dry ice in the world to conceal the rot of stupidity hovering over "13 Ghosts." With Embeth Davidtz and Matthew Lillard both overacting to a lower power in supporting roles, there apparently also aren't enough acting coaches.
A more fitting tribute to William Castle would have been to create a horror flick you could sit through without consistently squirming in abject loathing.
Clever one-liners supplant the lack of frights with cackling -- which you might as well do since, by the end of the movie, it's clear that the joke's on you.