Supernatural season 9, episode 13, “The Purge,” aired tonight, with the Winchesters taking an undercover case at a spa.

The episode opens with the death of a competitive eating champion. In a death reminiscent of a Doctor Who episode, the 300-plus-pound man is sucked dry of his fat.

Back at the bunker, things between the brothers are tense with Sam wanting to keep things strictly professional. Dean turns them onto the weird Adipose alien case and they head to Minnesota, where the sheriff has a pretty fantastic accent.

The sheriff points the brothers to the victim’s biggest competitor on the competitive eating circuit, though he has an alibi. It turns out his wife is a gypsy, though, and Sam finds a putsi bag with the victim’s hair and takes it.

That brings the wife to their motel, and she clears some things up: she and the victim were having an affair and the putsi bag was used for a blessing. She wanted him to win the competition so they could run away together.

Cut to a health club where a bride-to-be is working out after hours. She’s attacked by a figure with a dumb bell and has her fat drained as well.

The next day, Sam and Dean check out her body and find a strange suction mark. After an uncomfortable exchange, Sam heads to the morgue while Dean talks to one of the trainers. Dean sees the same strange mark on the trainer and does some digging on her. She’d recently lost a lot of weight after spending some quality time at Canyon Valley, a local wellness center. Sam and Dean head there, and Dean gets a job in the kitchen while Sam becomes a trainer.

It turns out the sheriff is also vacationing at the spa. She has a “cupping” session with Mariza, the club’s co-owner, but falls asleep partway through. It’s probably a good thing, though, since Mariza feeds on her suctioned fat. Not nearly as cute as the Adipose aliens, alas.

Back in the kitchen, Dean steals some pudding for later while Sam awkwardly teaches a yoga class. He walks around the room and notices the suction marks on all the clients’ backs. Meanwhile, Dean eats the pudding, but it’s laced with something and he passes out.

After his yoga class, Sam runs into the sheriff — who is thankfully not dead. She greets Sam as an FBI agent, but Sam deflects since the sheriff is with the other club co-owner, Larry, and takes an SOS call from Dean.

Sam finds Dean in the basement, drugged, so confronts the chef about the pudding. According to the chef there are supplements in the pudding, but Dean recognizes them as roofies. Next, the brothers talk to the sheriff and after a touching conversation, she shows them her suction marks.

Meanwhile, Larry noticed the interaction between the sheriff and Sam, so dug around the Impala’s glove compartment and found the Winchesters’ box of IDs. Realizing they have a bad case of hunters, the husband and wife plan to get rid of all the evidence. As Sam investigates the cupping procedure, Dean catches Mariza feeding on fat out of the fridge and ties her up.

Mariza is a Peruvian fat sucker — a parasite. She’s not killing people; the guilty party is her brother, Alonzo, who works in the kitchen. Larry confronts Alonzo to kick him out, but Alonzo kills him.

Mariza wanted to co-exist with humans and set up Canyon Valley with Larry to feed while helping people. Alonzo, though, wasn’t interested. Mariza demoted him to the kitchen, and he became so hungry that he started killing people. Mariza promises the Winchesters she’s on their side and tells them how to kill her brother as proof.

The brothers head for the basement, but the lights have naturally been cut. They take flashlights and split up because that always works well. Sam finds the chef dead and is ambushed by Alonzo. They fight and Alonzo takes the upper hand. He’s about to feed on Sam’s zero-percent body fat when Dean arrives. He cuts off Alonzo’s tentacle, killing him.

With the case closed, Sam empathizes with Mariza, who has lost her entire family in an afternoon. But while Dean, who has apparently returned to his season 2 view on monsters, is ready to kill her, Sam convinces him to let her go.

The episode closes back at the bunker with another unsettling broment. It’s set up as a conversation that the brothers really need to have: When Sam mentions his comment about not being brothers, Dean replies that while he might not always think things through, he does the right thing.

Sam retorts that that attitude is the problem — that because Dean believes himself Sam’s savior, he’s convinced himself that he’s doing more harm than good. But he’s wrong. Dean saved Sam not for Sam’s sake, but for his own. Dean, Sam says, is all too happy to do the sacrificing when he’s not the one being hurt by it.

Dean replies that if the situations were reversed, Sam would’ve done the same as Dean. We’re ready for it, writers. We’re ready–

Sam says that he wouldn’t do the same and leaves, and we’re left about as cold as Dean looks before the screen fades to black.

Watch a promo for the next episode

What did you think of ‘Supernatural’ season 9, episode 13 ‘The Purge’?