At Isis, Chloe is supervising a group of individuals with meteor powers who are discussing their problems. One of them, Mary, is talking and admits she could use some friends but doesn't believe that it's going to help them with the public. Another one, Randy, insists that he's just happy to be there. The meeting ends and Chloe thanks them all for coming.
Mary is walking home along the street that evening when she hears someone behind her. She comes to a street with the light out. Using her ability, she activates it and then pulls her off into the darkness, screaming.
Chloe meets Clark at the Daily Planet for an evening together, but he's busy listening to the police radio. She leaves and he distractedly says goodbye. He hears a report of a jewelry robbery and runs to the store to take out the robber at superspeed, then helps a boy against two bullies. He then hears a report of a commotion at the Ace of Clubs and jumps up to find the place in chaos and Davis among the injured buried in the devastation. As he's taken out, Davis gets up but says he doesn't remember anything. He prefers to leave, and John arrives to talk to Clark. A non-powered John is now using the name John Jones and working as a police detective. John assures Clark he's doing what he can but neither one of them knows anything, until Clark spots a cell phone among the evidence.
Jimmy is at the Planet checking the police web sites about the new invisible "Good Samaritan" that is breaking up crimes. Clark dismisses it as an urban myth and Jimmy notices he has the cell phone. Clark figures it may have recorded what happened and Jimmy hooks it up to the computer. The recording shows some force sweeping through the club at superspeed, attacking everyone.
Clark goes to Isis to see Chloe and explains what happened and how someone with superpowers is involved. He sees Chloe's sign-in list of clients but she refuses to let Clark accuse any of her people without people. An angry Clark blames himself but Chloe refuses to give in.
Davis is at the hospital washing off the blood but discovers he isn't injured. Shocked, he sits down on the floor. The next morning, Davis takes a blood sample and starts to leave, but Jimmy arrives. Davis knows him from Chloe. Jimmy is trying to get a lead on the club massacre and he asks to ride along with Davis. Davis is reluctant but Jimmy convinces him to bring him along.
Clark has memorized Chloe's list without her permission and shows it to John. John wonders if he's obsessed then notes that there have been five other murders in the last few months. John promises to investigate the names and notes that Davis has been the paramedic to arrive first at all the crime scenes.
Davis is examining Mary's body in the morgue and removing blood and skin from underneath its fingernails. Chloe arrives to see her and Davis assures her that Mary's death wasn't her fault. She plans to find the suspect but notices that Davis is acting odd. He pauses and then admits that he might be the killer. At Isis, Davis explains that he's been having blackouts and was covered in other people's blood. Chloe doesn't believe it, much to Davis' surprise. He says that the blackouts have been happening ever since he was a kid, and part of why he bounced through foster homes. Chloe promises him that they'll find the killer.
Randy and the others hold a candlelight memorial at the alley where Mary was killed. Chloe arrives and warns them not to turn on each other, and to see if any of them know anything. They think she believes it's one of them and say that a cop has been checking them out. They wonder if Chloe gave the cop their names.
Clark is at the hospital and talks to Davis, who still says he doesn't know what happened. Clark accuses him of knowing more than he's saying and confronts Davis with photos of corpses that Clark took from his locker. Davis says that there's another figure in the background of the photos, and suggests Clark might be involved. Clark denies it but Davis suggests he stay closer to home.
At the Planet, Clark is going over Davis' test records when Chloe confronts him about giving John the names. She accuses Clark of turning against others with powers but he insists that he's earned her trust. Chloe disagrees, and Clark asks her to use her mental abilities to analyze Davis' tests. She checks them out and realizes that the skin and blood under the victims' nails match Davis.
Jimmy arrive at the morgue and finds Davis there waiting for him. They go out and hear a police report of a murder. They arrive at the scene and Davis finds a set of keys. He tells Jimmy to stay with the ambulance and proceeds down the street. Jimmy hears signs of a struggle and then sees a superspeeding figure. He goes to investigate.
Clark and Chloe are going over the evidence and Chloe wonders if the victim grabbed Davis when he arrived on the scene as an EMT. However, she's forced to admit Davis is in a perfect permission to commit murders. Chloe locates the ambulance location and they hear Jimmy making his report. Clark superspeeds to the crime scene and finds Jimmy gone. Davis stumbles out of the darkness but some shadow forces grabs him and drags him back. Clark goes to investigate and sees a shadow figure choking Davis. The figure runs away and Jimmy arrives to explain he saw the shadow creature too. It moves around them and then attacks Jimmy, knocking him down next to another victim. Clark uses his x-ray vision to spot the creature attacking Jimmy and throws a tire to knock it away. The shadow creature solidifies to reveal… Randy. Jimmy gets his photos while Davis staggers up to them.
The next morning at Isis, Clark arrives to apologize to Chloe for losing perspective. Chloe admits she can be stubborn and Clark in turn notes that he was upset she trusted someone more than him. He wonders how she can trust people she doesn't know and she shows him her file on the 327 meteor-infected people she's documented. She hasn't been able to save any of them and notes that they need to protect the infected as well as their victims. Clark worries that some day she might trust the wrong person.
Chloe meets with Davis who thanks her for standing by him. He wonders if she helped him out of a code of ethics or something else. She says she shouldn't be there and doesn't feel guilty, but wants to make sure it stays that way and says she doesn't want to see him for a while.
Clark talks to John and wonders how he could have been wrong about Davis. John warns him that he has to slow down and make sure he's not spotted, because there are millions of people in Metropolis. He's been running interference for Clark but notes he can't do it forever. Clark promises to be more careful and Jimmy arrives to ask John if he knows anything about the mystery Good Samaritan. John encourages him and says he'd be glad to hear any hard evidence. After John leaves, Jimmy insists that he'll prove that the mystery hero exists.
Randy is restrained in a room when a woman comes to see him. Randy is happy to finally get recognition and the woman says her boss Tess Mercer is putting together a team of super-powered individuals. The woman notes that Randy is just a copycat and they have film of him at an arcade when one of the murders occurred, where a crucifix was taken. Randy tries to bluff it out but Tess' assistant doesn't buy it.
Davis gets into his ambulance… where there's a crucifix hanging from the rear view mirror.