The “Teen Wolf” pack hopes that history will help them defeat their new enemy. Gerard (Michael Hogan) told the original story of the Beast of Gevaudan’s defeat by Marie-Jeanne Valet (Crystal Reed) in Season 5B, episode 18. His knowledge comes at a good time. While Lydia (Holland Roden) listens to the story, the rest of the pack needs to find a way to take on the Beast. The creature arrived at the end of episode 17 and started attacking the lacrosse game attendees. After they discover his true identity, the Beast will be even more difficult to kill.

The episode kicks off in the 18th century in a French village. Two soldiers, Sebastien (Gilles Marini) and Marcel (Daniel Bonjour), are caught in the rain. They find a cabin for shelter, but the resident tells them that they shouldn’t hide there. A demon wolf is haunting the village. British soldiers surround the house, but the Beast is apparently not with the redcoats. They all quickly get massacred.

Parrish (Ryan Kelley) interrupts Gerard’s story to leave. He doesn’t want to be part of this, but he might not be their only option. Chris (J.R. Bourne) and Gerard think Lydia could defeat the Beast, so they tell her the rest of the story.

Sebastien returns to his village with Marcel, and miraculously they’re fine after the run-in with the Beast. They also don’t mention seeing the creature. Instead, Sebastien says his sister Marie-Jeanne (who happens to look just like Allison) should join the hunting party for the Beast. After all, she is the best hunter. She claims she only goes after animals, not rumors. When someone brings in a dead child a few seconds later, it’s clear that the Beast isn’t a tall tale.

She goes with the men, and the Beast takes out most of her hunting party. She comes face to face with the creature, but he knocks her crossbow out of her hands. She is cornered with only a small blade to defend herself.

Henri (Lachlan Buchanan) jumps in front of her and throws down some mountain ash. It provides a barrier for their escape.

In the present day, Liam (Dylan Sprayberry) is in bad shape, but with a kiss, Hayden (Victoria Moroles) manages to absorb some of his pain so he can heal. Meanwhile, Malia (Shelley Hennig) is trying to find Stiles (Dylan O’Brien). Everyone else is running and trying to hide from the Beast. Scott (Tyler Posey) saves a girl by trying to block a classroom door. It allows the girl to get out, but Scott has to face the Beast.

Lydia can feel something is wrong. Her friends need help, but she needs to know how to defeat the pack's enemy. Gerard says that Henri brought Marie-Jeanne back to his house in the woods. He is a werewolf hunter, and he offers to teach Marie-Jeanne his survival skills. “I do not care about surviving one,” she says. “I want to know how to kill one.”

Marie-Jeanne pours drinks for all of the men in her local pub. They toast the dead and Marcel breaks his glass. Marie takes him to the well to wash his hand, and Marcel gives her a key to the cellar. He says she’ll find that she is looking for there. She goes in alone and is horrified to find a pile of dead bodies.

She returns to Marcel and aims an arrow at his throat. He encourages her to kill him, even begs her. She realizes that he is covering for the killer. While she is outside, something she put in the drinks makes her brother Sebastien start choking, and his eyes go blue. He is the Beast.

He manages to control himself and stop the transformation. Marie quietly confronts him, and Sebastien says he kills everyone who gets in his way. He threatens to tear apart everyone in the pub if she tells anyone. He gets up, kisses her head and claims she isn’t capable of stopping him.

Marie-Jeanne goes to Henri for help. They need something that uses the Beast’s weight against himself. They create a special spear, and Marie-Jeanne hunts her brother for three years. In their final encounter, he easily pulls her arrows out of him and transforms into the Beast. However, she has her spear hidden in the snow. She pulls out her weapon and the Beast can’t even stop himself. He is impaled before he even realizes she has the blade.

He assumes he’ll heal, but as he starts coughing up black liquid, he discovers that this injury is different. His sister reveals that the spear was made with wolfsbane and mountain ash and was forged with her own blood under the full moon. He realizes he is dying and swears history will remember him. Marie-Jeanne and Henri burn every physical memory of Sebastien.

Gerard and Chris say that if the current Beast remembers Sebastien, the teenager whose body he is resurrected in will be gone. Lydia points out that Marie-Jeanne never worked alone. She had the town behind her. Lydia says she needs Parrish, who is shown leaving his badge on the Sheriff’s desk.

They tell her Parrish is dangerous because his powers work differently. He is controlled by them. Lydia asks why Gerard cares. He’s never been on their side before. Gerard explains that Marie-Jean Valet married Henri, and she took his last name: Argent. He says their name will be remembered for killing the Beast. “But I’m not an Argent, and I’m not Allison,” Lydia says.

Meanwhile, Scott runs to the library and finds more students hiding. He tells them to go to the second floor of the library. Scott goes into alpha mode in front of his classmates to battle the Beast.

Scott takes a few hits, but back up arrives quickly. Liam comes at the Beast from behind, and then Braeden (Meagan Tandy) comes in with her shotgun. After about a dozen bullets, the Beast breaks through the window and runs away. “You didn’t seriously think you stood a chance against that thing, did you?” Braeden asks.

“No, but I got its scent,” Scott reveals.

Scott runs into the parking lot and follows the Beast’s scent to a car. He breaks into the trunk to find a pair of shoes. The soles are covered in blood and match the bloody footprints that the Beast’s pawprints turned into when he showed up at the hospital in episode 11.

Mason (Khylin Rhambo) shows up and asks why his friends are breaking into his trunk. Mason is the Beast, but that doesn’t mean they have him yet. Corey (Michael Johnston) grabs Mason and makes him invisible.

“Teen Wolf” Season 5B airs Tuesdays at 9 p.m. EST on MTV.