It's like Groundhog Day on an astronomical scale.

David Dinwoodie made a mistake. His experiment opened up a rift into an alternate universe. Not everybody flew into the new reality. Those that did were confused. The things we do/don't do in this reality has a major effect on our lives in the alternate universe.

Graham is too shy to make a date with Natasha until his house is wrapped in a time warp. Then he learns from the future to enjoy the present.