Reaper (2007)

Season 1: Episode 6

Sam discovers that demons don't work on Halloween. Unfortunately, a depressed Devil decides to make Sam's assignment even harder to cheer himself up. Sam and Sock capture one soul, Leon, an escapee who killed someone over a hundred years ago, but before Sam can return him Leon tries to convince them that he's changed. The Devil then sends Sam to recapture a second soul, a serial killer who plans on starting a new murder spree.