The origin story of the little metal band that could.
This review may contain spoilers. I can handle the truth.
A variation on Wicker Man (with a hint of Logan's Run in that at 72 your crystal goes black and you need to enter a new vessel to be reborn), where a cultist on a sort of Rumspringa brings the friends he's made on his excursion back to his people as offerings.
Flame going out means bad luck when you suicide.
Pelle killed Dani's family so she'd be forced to go.