When Sam and Sock capture Leon, an escapee who assassinated President William McKinley over a hundred years ago, the soul convinces them he's changes after being through therapy.  When his soul is transported to the DMV via its vessel, a snow globe, they find out Gladys (and all other demons) are on vacation for Halloween.  Later, the two release the soul, and Leon tries to help Sam his next demon only to hold them at gun point knowing he'll go back to hell.  Meanwhile, we find out the Devil is depressed on Halloween because it's the one day people are no longer afraid of him.