In “Angel Heart,” Supernatural gives us a stand-alone episode that ties up some loose ends from Season 10. It’s fun to see the Winchester brothers helping out Cas. Dean can benefit from helping a friend in order to tone down the murderous impulses of the Mark. It also gives Sam the chance to get out of his head and away from his own Mark-related obsession. When we see that Claire Novak’s mother Amelia is being held captive by a supernatural creature, “Angel Heart” reminds us that there are still lots of monsters to hunt in the world of Supernatural.