Luke Honey, a former elephant hunter, is invited on an annual prestigious hunting trip on Mr. Liam Welloc Esquire's estate in Washington. He arrives at the Black Ram Lodge and meets the other men, all of whom are extremely wealthy. Dr. Landscomb owns the lodge with Mr. Welloc, and Lord Bullard is a British war veteran who came with Mr. Wesley. Mr. Williams is a Texan rancher who came with Mr. McEvoy and Mr. Briggs.

Mr. Wesley and Lord Bullard recount a tale from a hunting trip in Mexico where an American ex-patriate leads them to a fortune teller who predicts a dark cloud and a cave in their future. The next day, they go on a hunting trip after a giant hog, following it all the way to a cave system the locals say is evil, before returning. Luke interrupts the story, calling them out for turning around in the face of their fear, and Mr. Wesley challenges him to a duel for his honor.

Mr. Welloc intervenes, telling them this trip is the lodge's most sacred tradition. Whoever kills the black stag, which has never been done, will win a nearly priceless rifle from 1851 and ten thousand dollars sterling silver. Later that night, Luke and Mr. Wesley meet for a fistfight in the barn. Luke gets a good hit in Mr. Wesley's ribs below his heart, but Mr. Wesley is stronger than Luke predicted. He wins the fight, landing Luke on his back.

The next day, the men go into the woods with the lord of the stables, Scobie, and his nephew, Arlen. The hunting party kills a medium-sized stag, and later, Arlen comes across signs of a large stag ahead. They camp out for the night, where Mr. Wesley seems to be doing poorly, and hear a pack of wolves.

Scobie says that people don't hunt here anymore unless they're lords or foolish townies because Satan roams the woods. The hunt they're on predates the lodge's establishment and someone is either seriously injured, killed, or lost on each trip. Scobie tells them about the origins of the black stag. In the past, the Blackwoods settle in Olde Towne when it is founded and run a fur trade out of Ransom Hollow, the woods Luke and the men are currently in. The town says that the Blackwoods aren't religious and consort with the devil. The town believes the elder Blackwood once had sex with the devil in doe form, and the spawn, called Blackwood's Baby, is said to be the stag Luke and the men are currently after.

The men enter the deepest part of the forest with a thick fog. The British go ahead and then the dogs start howling amid gunshots. The stag appears through the trees but it is far too big and moves in a top heavy manner. One of the horses hits Mr. McEvoy, twisting his ankle. The dogs are all dying or dead and the stag takes two of them, impaled on its horns, into the woods when it runs off.

The men regroup and realize Arlen is gone after finding his shoe near the tracks of the stag. The uninjured men keep searching for the stag while the rest return to the campsite. Luke and Mr. Williams separate for water and then a heavy fog suddenly settles around them. Luke realizes he is alone and there is a muted glow ahead of the waterhole. He follows it until he finds a statue of a horned man in a thorned grove. An invisible force strikes Luke down. The statue expands and Luke hears terrible voices in his head talking about how fresh boy blood is best. Luke tells it to take him instead of Arlen, but the voice says Luke already belongs to it.

Mr. Wiliams finds Luke who is laughing like crazy. Mr. Williams says the rich townies put statues like this up all over the estate, and there are stories about rituals and sacrifices in the hills. They return to the others, and in the morning, Mr. Wesley is dead from the internal injuries Luke gave him in their fight. The men debate going back, and Scobie stomps into the forest to continue on his own. Mr. Liam Welloc says they tempt fate by staying and that the Sheriff has experience with these matters. Luke knows no one is going to search for Arlen when they get back because the yearly sacrifice has already been made.

The men give up and turn back toward the lodge, but Luke returns to the forest. The stag runs past him, followed by Scobie who tells him Arlen is as good as gone. Scobie and Luke keep searching still and camp out for the night. Luke wakes up with a knife pressed to his throat, and Scobie tells him he made a deal to exchange Luke for Arlen.

They make it to a clearing that Scobie has prepared with ancient runes, but Luke hits Scobie and pushes him into the middle instead. The stag comes and starts to eat him while Luke watches.