Many changes made for the series were done in the name of sustaining narrative television. The TV series follows the basic outline of John Ajvide Lindqvist’s novel, as well as Tomas Alfredson’s 2008 feature involving a young boy whose new friend is a vampire, as well as 2010’s American remake directed by Matt Reeves, “Let Me In.” From there, both movies take different routes to tell their story. Which version is right for you? It depends.