Midsomer Murders S23E01 - The Blacktrees Prophecy

Deep in Blacktrees Forest is a bombproof shelter built by a man named Warren Kaine. His extreme paranoia has drawn other survivalists to the village, and now a doomsday prepper group meets weekly. But after the controversial ousting of a member, Warren has a target on his back. Preaching survival at any cost comes back to haunt him as the Blacktrees Prophecy claims its first--but not last--victim.