In the Las Vegas desert, a CSI team is going over a crime scene. A man in a sports car pulls up: Police Detective Sheppard. A reporter wants to know if a serial killer is responsible but Sheppard ignores her. The coroner informs Sheppard the victim is apparently a white male and someone dropped the body off in an older-model pickup with a radiator leak. The victim is dead the same as the other seven: twisted and aged with a strange hand-shaped chest wound.
Back in Vegas, Sheppard drops in for an autopsy of the victim. There's no indication of chemical residue or a disease, and on the last seven victims there were indications of radioactive residue. Dr. Jennifer Keller, the doctor doing the autopsy, tells him she'll report when she has more info. Sheppard isn't thrilled with having a young doctor on the case. At the station, Sheppard puts out an alert for anyone displaying radiation symptoms.
In a cheap hotel room, a man is throwing up. He makes a call and informs the woman at the other end he's bleeding from the nose and generally feeling bad. After he hangs up, he pounds on the wall to complain about the person in the next room playing loud music. When they ignore him, he staggers next door and a Wraith answers the door.
The next day at the station, Agent Woolsey of the FBI drops in to see Sheppard. Woolsey refuses to discuss the government's interest but notes that the killer is becoming either more careless or more bold. The newest victim shows no sign of radioactive isotopes like the previous seven. Sheppard goes to see a nurse who has a report on the man at the hotel, who stopped in for treatment. The nurse thinks the man was displaying symptoms similar to radiation poisoning. She tries to flirt with him but he makes a quick exit and goes to the hotel. The clerk says the sick guy checked out the previous day.
That night, the Wraith is making up his face and applying facial prosthetics, dental fixtures, and contact lenses to pass as human. He steps out… leaving the sick guy's aged body behind. He's unaware that Detective Sheppard is following him. The Wraith goes to a casino and joins a game of high-stakes poker. He wins big but Sheppard arrives and interrupts the game to deal himself in. It comes down to Sheppard versus the Wraith. The Wraith raises and Sheppard has four of a kind. The other players figure the Wraith is bluffing, but Sheppard folds. When one of the players tries to stop the Wraith from leaving, it throws the man aside, slams Sheppard to the ground, and runs out past the security guards. Sheppard gives chase as it runs to the roof… and leaps off. It falls several stories, gets up, and runs away.
Sheppard goes back to the Wraith's hotel room and finds the corpse and the make-up gear. He also finds a duffel bag full of cash. Woolsey and his men pull up, and want Sheppard to come with them. They head out to a military base in the desert and a man arrives: Dr. Rodney McKay. McKay figures Sheppard can help them and goes in to talk to him over Woolsey's objections. McKay reviews Sheppard's entire life history, including the fact he was a helicopter pilot in Afghanistan who got people killed when rescuing a mission. Then McKay tells him that he once met a different Sheppard. He talks about wormholes, aliens, and infinite parallel realities.
The Wraith is in a trailer remembering a battle in space that he was part of.
McKay shows Detective Sheppard a ZPM and a chair that they found in Antarctica and used to defeat a Hive ship that attacked Earth two years ago. There are more aliens from another galaxy and they know about Earth. He also shows Sheppard a Wraith Dart that they recovered, and explains the serial killer is an alien Wraith. He shows Sheppard a captive Wraith, Todd. Todd is delirious from starvation and seemingly rambles incoherently. He says he knows the future and recognizes Sheppard. Keller is there, and appears to be involved with McKay. McKay notes that Sheppard tracked down the killer Wraith before they were ready to hush things up. They're not sure what the source of the radiation is found on the first seven victims. They figure the killer is exposing himself to radiation and needs to feed to heal the resulting damage. McKay figures the killer Wraith has salvaged some parts from his crashed Dart and needs more materials to repair it, along with the money he's making from playing poker. McKay excuses himself to talk with Zelenka, who is giving a briefing and warning that the Wraith may be creating a bomb. McKay disagrees with Zelenka's assessment, figuring the Wraith is building a device to send a message to the Pegasus Galaxy.
Afterward, McKay thanks Sheppard for his cooperation but Sheppard wonders why the Wraith killer is leaving bodies in the open and abandoned the money. As Sheppard leaves, McKay says that they accidentally opened a rift in space-time and he met a team where Sheppard was a hero and saved the world several times over. He thinks that one incident may have altered Detective Sheppard's life and figured he had enough strength of character to handle the truth.
Back at his office, Sheppard packs up and tells his boss that he's quitting. He drives into the desert with the money he took from the Wraith's hotel room. Sheppard remembers back to what McKay said about the Wraith feeding on humans and how he would need a massive power source to send a message. He also remembers a pickup truck with a leaky radiator near the hotel and a trailer next to it.
At the government base, Woolsey, McKay, and Zelenka are trying to figure out what the Wraith is up to when Sheppard calls and informs them he's found the trailer near the power lines, and the Wraith is tapping them for the necessary power. Sheppard has tracked down the trailer but McKay tries to warn him not to engage. Sheppard loses the signal on his phone while the government launches an air strike. Sheppard drives up to the trailer and gets his gun out. As he approaches, the Wraith opens fire and Sheppard ducks for cover. The two exchange gunshots and then the Wraith comes out. Sheppard gets to his car and reloads but is hit. The Wraith comes around and sees Sheppard, wounded and out of ammo. The Wraith prepares to feed but spots the two fighters coming in. He runs for the trailer and tries to send the signal. The fighters open fire and take out the trailer. McKay analyzes the signal and determines it has the coordinates for Earth. Worse, the device created a rift in time and space. Zelenka warns that the signal would be stronger in any other reality it reached through the rift.
In the desert, Sheppard looks at the burning wreck of the trailer then collapses, dying, on the ground.