In Montana near Great Falls, a man is walking along the shoulder of the highway at night. A drunk driver is coming up behind him, passes out at the wheel, and slams into the pedestrian. When the driver realizes what he's done, he quickly drives away, leaving the corpse on the road.
The next morning, a state trooper, Jack, pulls over when he spots the body. He checks for a pulse, confirms that the body has frozen overnight, and then goes back to his car to report the incident. In the meantime, the pedestrian's corpse thaws out and his wounds heal. When Jack turns around, he's surprised to discover that the body is gone and footprints in the snow lead into the forest.
At the Letters base, Sam discovers that he is still choking up blood. He quickly washes it down the sink as Dean comes in. Dean notices Sam acting awkward and asks if they've heard anything from Kevin or Castiel. Sam admits that they haven't and Dean figures that they need to do something before they both start climbing the walls. Having checked the newspapers, Sam shows Dean an article about an alleged zombie sighting in Montana. They drive there and talk to Jack, who insists that he must have seen a zombie. As they talk, the dispatcher gets a report about a man mauled by a grizzly bear near Livingston. Jack confirms that the man in the photo is the same one that he saw, and Sam and Dean tell him to stay put and deal with any other zombies while they investigate.
The brothers talk to the Livingston coroner, who tells them that the body had no ID and no fingerprint records on file. When Sam notices a torn spot in the man's side, the coroner figures that some bird must have been feasting on the body. As the brothers talk outside, the dead man comes back to life and tries to leave. The Winchesters spot him and drag him into an autopsy room, demanding answers. The man says that all he can remember is that his name is Shane and he keeps dying and coming back to life. When Dean threatens to shoot him if he doesn't give them more, Shane tells them to do it but to make sure that he stays dead. Dean reluctantly holsters his gun and tells Shane that they're coming with them.
Back at their motel, the Winchesters run the usual tests to confirm that Shane isn't a demon or a shapeshifter. He tells them that he can only remember back a few years, and only thinks his name is Shane because people call him that. The first time that Shane can remember dying is in an avalanche in Europe. When he started dying and coming back to life every day, he moved to a private cabin in Montana so people wouldn't notice. However, a couple of nervous pot growers spotted him and shot him dead. He moved on after that and was hit by the truck. When Shane goes to the bathroom to clean up, Sam suggests that Shane might be cursed and proposes that they get him another room while they figure out what's going on.
That night, Shane is sleeping when a woman in black leathers appears in the motel room and sits on the bed next to her. She strokes his face and Shane wakes up, grabs her hand, and asks who she is. The woman is surprised that Shane doesn't recognize her and draws a knife. Shane throws her off the bed and launches a complicated martial arts maneuver. When Sam and Dean barge in, the woman trips Dean with a kick and telekinetically sends Sam flying back out the door. Shane finally manages to subdue her and holds the knife to her face. When he asks who she is, the woman says that she's now his worst enemy and fades away. As Shane tells Sam and Dean what happened before he got there, he suddenly collapses from a heart attack.
The next morning, Sam and Dean watch over Shane's body and wonder what to do next. A woman, Hayley, arrives at the door with her son Oliver. She explains that the coroner told her that the brothers were the last one to see Shane's corpse. The woman introduces herself and explains that Shane is Oliver's father. When the brothers wonder why she's looking for it, Hayley sees Shane's body on the bed, tells her son to stay with the Winchesters, and goes to Shane's corpse. Afterward, she goes outside and tells the Winchesters that she was mountain-climbing with friends in Europe when she was caught in an avalanche. Shane rescued her and took her back to civilization, and they fell in love. After one night together, Shane had a heart attack the next morning. When he came back to life, Hayley ran off in terror. Later after she gave birth to Oliver, she hired private investigators to find Shane but they had no luck. She finally gave up until a few months ago. Shane comes out of the motel room and Hayley calls Oliver over to meet his father.
As Shane talks with Hayley and Oliver, Sam checks the Internet and tells dean that Shane is actually Prometheus, the Titan of Greek Mythology. Prometheus stole fire from Zeus and gave it to mankind, and Zeus chained him to a mountain and made him die every day, sending an eagle to eat his liver. Prometheus would then come back to life only to suffer the same grisly death the next day. Sam figures that the woman who attacked Shane is Artemis, the Goddess of the Hunt and daughter of Zeus, and the dagger she had can kill gods. They call Shane in and explain who he really is, and Sam suggests that they get his family away for their own safety. As they discuss the situation, Hayley rushes in, carrying Oliver's body, and explains that he fell off the swing. Sam realizes that Shane's curse has been passed on to his son.
Sam and Dean take Shane, Hayley, and Oliver to the Letters base, and Hayley explains that Oliver started dying and coming back to life when he turned 7. Sam realizes that 7 is an important age in Greek culture and figures that the curse is genetic. When Hayley wonders what they're talking about, Sam tells her who Shane really is and that they're Hunters. She wonders how they usually handle curses and Dean tells her that they summon the person, ask them to lift the curse, and beat them up if they don't. Hayley doesn't think that they can take on Zeus and goes to check on Oliver, waiting for him to resurrect. Dean tells Shane that whether he helps them or not, the brothers are going to try and summon Zeus and have him lift the curse. Shane agrees to help them.
The group goes through the research books and Dean finally locates a reference to Drakopoulos, a Greek hunter who battled Zeus. According to his journal, he used the ash from a tree struck by lightning to bind Zeus into a circle. To summon Zeus, the brothers will need fulgurite and the bone of a worshipper of Zeus. As they try to track down the ingredients, Hayley reads the rest of the journal and realizes that it ends without revealing if Drakopoulos won or lost. Dean says that it's the best chance that they have while Sam finds an obituary for two Greek patrons who died nearby. As he leaves with Shane, Dean prepares to make an extensive search for fulgurite. Hayley points out that it's used to make cheap New Age jewelry and should be easy to find.
As Sam and Shane dig up the graves, Shane asks Sam why he's helping them. Sam reminds him that Prometheus saved Mankind by restoring fire to them and he feels that he owes him. Shane figures that none of it means anything if he can't save Oliver.
As Dean and Hayley drive to the jewelry store with Oliver sleeping in the back, Dean tries to reassure Hayley that everything will work out. She points out that they'll be asking Zeus for help and Dean warns her that as a god, he won't help them. All they can do is get him to do what's right.
Everyone returns to the Letters base and Dean and Sam cast the summoning spell. Zeus appears in a burst of lighting and looks at them with amusement, and dean suggests that he lift the curse on Oliver so they can all go home. Zeus ignores Dean and tells Shane that he's been looking for him. The god realizes that Oliver is cursed as well and Dean asks if they have to do it the easy way or the hard way. Zeus agrees but only if they break the spell, but Dean refuses and tells him to cure Oliver first. When Zeus says that Oliver will suffer as long as he's trapped, Dean stares at him for a moment and then tells everyone to leave.
As Dean and Sam walk away, Zeus tells Hayley that Oliver needs him to lift the curse. She runs over and breaks the spell circle, and Zeus steps out and blasts the others away. He focuses on Oliver and Dean and Sam try to sneak up on him, but Artemis comes in and pins them to a pillar with a gesture. Meanwhile, Zeus wonders if Shane has suffered seeing Oliver die, and then slams Oliver to the ground and says that the pain he suffered is a thousand times worse. He tells Oliver that he has a special job for him and then tells Artemis to dispose of Sam and Dean. As she leads them away, Sam tells Dean that Artemis is the patron god of hunters, but that she's lost her touch. Artemis slams the brothers into the wall and insists that she's still worthy of worship.
Back in the main room, Zeus slams his hand into Shane's chest. Hayley and Oliver watch in horror as Shane screams in agony.
Artemis is ready to kill the Winchesters but Sam points out that it took her seven years to hunt Shane down. He claims that Shane told them about his love affair with Artemis. Artemis hears Shane scream and Sam tells her that Shane told them that she let Prometheus go free so that they could continue their love affair. When Zeus saw the zombie article, Artemis knew that he would send her to Montana.
Finished with Shane for the moment, Zeus turns to Oliver and tells him that he should enjoy being an immortal, even if he has to keep dying and coming back. As he prepares to kill the boy in front of his parents, Artemis comes in, bow drawn, and tells her father that it's time to stop. Zeus insists that he's torturing Shane because he prevented the Greek Gods from ruling the world. Artemis tells her father to let Shane go, but he says that he's her father and she has to obey him. Artemis says that he's not the father she knew and shoots him. However, Zeus snatches up Shane's body and lets it stop the arrow. Smiling in triumphant, Zeus tells Shane that he will put Oliver up on the mountain to suffer for an eternity. Bracing himself, Prometheus grabs the arrow and pushes it out his back and into Zeus. Zeus screams in agony before dying in a burst of lightning. Artemis runs to Shane's body and pulls the arrow and looks up at Hayley, looking down at her lover. The goddess then teleports away with the body of her father.
Later, the Winchesters give Shane a hunter's funeral pyre. Dean gives Hayley a comforting hug, while Sam suggests to Oliver that they get ice cream sundaes. Olive quietly says that he wants to stay.
As the Winchesters drive off, Sam admits that he got lucky figuring out the relationship between Artemis and Shane. He tells Dean that he was naïve to think that he could survive the ritual to seal Hell's gate, but Dean promises him that he's not going to die. When Sam reminds him that none of their friends and family chose death, Dean promises his brother that he'll die of something normal after a long and happy life.
When the brothers get back to the motel, Dean waits until he's alone and then sits on his bed and prays to Castiel. He tells the angel that Sam is covering things up but it's clear he's having a hard time, and asks Castiel to watch over him. When Dean gets no response, he wonders where the angel is.