There are lots of movies about time travel, from the asinine Land of the Lost to the political The Time Machine and Sleepers, to the edgy Time Bandits and 12 Monkeys. Most of those have a gizmo or contraption that causes them to travel through time, but what if you just “hopped” without having any control over it? One minute you were in contemporary Manhattan then in the blink of an eye you were in Los Angeles in the middle of a Vietnam war protest march?
Henry works as a research librarian at a public library in Chicago, though presumably he has frequent absences from work as he time travels without any ability to control it. His travels all seem to be somehow related to his own history, however, and indeed at one point in the film he observes “I often go back to the same places, to places that are important to me, it’s kind of like gravity or something.”