This turns out to be a decoy plot. But it could have gotten people into the theater without blowing all the twists of the main story that follows. Harrison Ford plays Norman, Claire's workaholic professor husband, whose late father was himself an academic star. Trying to move out of Dad's shadow, Norman works late at the lab most nights, leaving Claire home alone. Only, she starts to suspect she isn't alone at all.
Doors open by themselves.
Computers and radios switch on and off. Though DreamWorks has already done a bangup job of spoiling its own flick, let's stop here with plot details. The script encourages us to second-guess what's going on in the house, and in Claire's mind. The film has more emotional subtlety and behavioral observation than your typical screamer. And at dinner with another couple, director Robert Zemeckis captures the way men talk to each other, and women do the same simultaneously, dividing the table by gender.