‘Onslaught’ Is a B-Movie That Gets the Blood Pumping

The title of Adam Wingard’s “Onslaught” holds true. As both a story of individuals holding on to their senses of self and an exercise in cinematic form, the picture dusts off its hands and gets down to business. A recurring set of title cards informs us that there is only so much time until some catastrophic event is to take place. The countdown is an obvious but effective ploy, particularly given the limited time span in which the story plays out. Was it my imagination or did the audience with whom I was seated collectively grip its armrests each time the clock appeared on screen?