"What if Warrior Cats
was a Southern American detective drama? This is a Warriors
version of opening to the HBO series True Detective. Maybe that combo doesn't make much sense, but I loved this opening so much I needed an excuse to reproduce it." Video Link
. Original True Detective open is here
And that lovely song is the Handsome Family's "Far From Any Road," from the 2003 album Singing Bones.
(Thanks to all who suggested!)