The plot (such as it was) is of a creature born of the last mouse on Earth, and of the life-cycle of that creature.
Not to be confused, of course, with Deus ex Machina, which is totally unrelated. Also not related to DeusExMachina.Video Games (note the extra "s" after "Game" and the reversed order). Nor of course with the later Deus Ex series of video games. All come from the theatrical term deus ex machina, Latin for "god from a machine", a special effect used when a production's plot involved a deity.