The episode begins with a girl arriving at a clinic and she is badly bruised. She collapses on the bed and moments later she starts acting hysterical. The attending doctor, Dante, asks her what she took and she starts speaking in Latin and we see that there is foam accumulating around her mouth. She then coughs out blood on the doctor’s coat and kicks one of the nurses with tremendous force. She then breaks her own arm trying to get out of the restraints and goes into cardiac arrest. She dies. The doctor tries to revive her but is not able to. Later, the doctor gives his statement to Tommy.
The doctor thinks that it is meth overdose and Tommy thinks that this is slightly too much for a meth OD. Megan arrives and talks to the nurse. The nurse tells Megan that she learned Latin in college and the girl said: “You all will die.” She also says that the room turned very cold when the girl was brought in. She subtly hints that this is a case of possession. Megan is pissed and asks the nurse to leave. At the medical center, Curtis and Ethan find it hard to believe that the death is only due to drugs. He is also finding it hard to believe that she broke her own arm. He tells Megan that the infected marks on the victim’s face could be because of sepsis. Megan dismisses Ethan’s theory. Tommy calls and tells Megan that they got a hit on the victim, Rebecca Banks.
Rebecca is a high school student, who has been picked up for meth possession. Tommy tells her that he is going to meet Rebecca’s parents and Megan decides to go with him. She tells Ethan and Curtis to do the autopsy. They meet Caleb and Laura Banks. Rebecca has two sisters and one of them is devastated on hearing about Rebecca’s death. Caleb tells them that he knew about Rebecca’s drug addiction and that is why he kicked her out. Laura tells them that Rebecca called once, wanting to come home, but the father did not allow. Tommy and Megan have nothing to say. Caleb then tells them that it wasn’t drugs that actually killed Rebecca, it was the Devil. At the medical center, Ethan and Curtis are about to begin the autopsy and they are stumped when they see that there is bruising all over Rebecca’s body.
These bruising are in the shape of the Cross. The thing that is worrying Ethan the most is that there was no bruise when they started the autopsy and when they finished, the bruises were everywhere. Megan has an explanation and tells them that ante mortem bruises are difficult to detect since they have a latency period. The cold air in the morgue brought them up. Curtis arrives with the tox screen results and tells them that there were no drugs found in Rebecca’s body. Megan is slightly surprised but she believes that there could be another explanation. She knows that Caleb thought his daughter was possessed and so when she came home, he tried to beat the Devil out with the cross and hence the bruises. She then says that the family lives in an old house, so, the air, the paint or some mold, anything could have caused her death.
She wants to find out what could have caused the cardiac arrest. Curtis tells her that at times excessive adrenalin could do that. He feels that Rebecca must have gotten scared of something. Megan tells Curtis and Ethan to check the house. Tommy meets Chelsea, Rebecca’s sister, at school and Chelsea tells him that Rebecca came home last week begging her father for help. She tells her that Rebecca was sick and she was too weak to stand by her sister. So she dropped her at the clinic and drove off. She also tells Tommy that their family lives under a great sin. Curtis and Ethan go to the house with a whole team of CSUs. Curtis checks the basement and finds a lot of things, including a bed with ropes tied to it. He also finds a bloody molar.
Ethan finds some letters and figures out that one of the girls had a pen pal. At the center, Ethan tells Megan that the tooth did not belong to Rebecca or her sisters. The tooth has radium on it. This means that the tooth is from the 30s where radium was used in toothpastes. Ethan then pulls up an article where a man named Atticus Aldrich killed his three daughters in that basement because he thought that they were possessed. Atticus is Caleb’s grandfather and he was diagnosed as a paranoid schizophrenic. Megan thinks that Caleb is repeating his grandfather’s sins by killing his daughters. Tommy calls surveillance so that they could bring in Caleb. The officer tells them that they are gone. We then see that the Banks family is in an old cabin and this time Chelsea is hiding under the bed and is “possessed”.
Her voice is different and she is very violent. Caleb calms her down. Next, Ethan arrives and tells Megan that the CSU found some epithelial under Rebecca’s nails and they have a hit, Todd Higgins. He was arrested for a DUI five years ago, but never convicted. Todd is now a pastor, and he tells Megan and Tommy that he was trying to help Rebecca. He shows some scratches on his body and tells them that he performed an exorcism on Rebecca because Caleb wanted him to. He tells them that he got a call from Caleb this morning saying that Chelsea is sick, but he refused to perform another exorcism. Tommy traces the number. In the cabin, we see that Caleb has tied Chelsea to the bed and Chelsea is violent, talking in a hoarse voice, contorting her body and she spits out blood.
Tommy, Megan and the team arrives. Chelsea takes the cross from Caleb’s hand and stabs herself several times and ends up puncturing her lungs. Megan tries to stop the bleeding and Chelsea tells her, “A quarter for your jacket pumpkin”. Megan is stunned. Megan inflates her lungs but just then Chelsea begins to aspirate. Later, the ambulance arrives and they take Chelsea. Caleb is under arrest. At the hospital, Megan sees that Hannah, the third daughter, also believes that Chelsea is possessed. She tells Megan that she too was a non-believer but her father made her see that her sister’s were Satan’s prisoners. At the interrogation, Caleb lawyers up. Tommy talks to Laura and tells him that Caleb did not believe in medications, but when the girls started with their female mood swings, she gave them St. John’s Wort.
She made them promise not to tell Caleb. Caleb thinks that taking medications is a way of letting Devil inside one’s body. Megan tells Tommy that this herb is known to remove traces of certain drugs and maybe that is why they couldn’t find anything in the tox results. They decide to run new tox screens. While waiting for the results, Tommy asks Megan about what Chelsea told her. Megan tells him that she always used to forget her jacket at school and one day her father told her, “A quarter for your jacket pumpkin. Now go learn something.” Tommy wonders how Chelsea could have known that. Next, Kate tells Megan that Rebecca’s and Chelsea’s blood is positive for PCP. Curtis tells them that this is not the garden variety, but this is an experimental liquid form that has been going through several trials in China.
Megan tells Kate that PCP cannot cause skin infection and conjunctivitis. Kate thinks that it could be the Steven-Johnson’s syndrome and since Rebecca and Chelsea were sisters, they had the same genetic make and could have similar reactions to certain drugs. Just then Ethan arrives and tells them that one of the girls was exchanging letters with Dr. Dante and the content is really explicit. They arrest Dante and Dante admits that he was sleeping with Hannah. They are shocked. Megan figures out that Hannah had access to the PCP and maybe she is the one who tried to kill her sisters. Megan and Tommy go to the house and find that Hannah is trying to kill her father. She tells her father that she loved him the most but her father always loved the other two sisters.
She then tried to drug them and get them kicked out; but once again they got all the attention. She then tries to kill herself, but the gun misfires. Hannah is arrested. At the hospital, Chelsea is awake and Megan is beside her. Megan then asks her about what she had told her at the cabin. Chelsea tells her that she doesn’t remember anything. Megan tells her that it is alright and begins to leave. Just then Chelsea says, “Now go learn something”. Megan is totally shocked. The episode ends.