|A girl named Meredith is walking along the streets of Chicago starts hearing noises and thinks someone is following her. Scared, she startes running towards her apartment. She lets herself in and relaxes, only to suddenly be attacked by a strange shadow-like creature and is killed, ripped into pieces with her heart missing. One week later, Dean and Sam, posing as alarm repairmen, take a look around her apartment. They find no signs of entry and nothing to give them any clues as to what killed Meredith. They do, however, find a strange shape on the floor in blood.
They head to a local bar where Sam comes across Meg, the girl he met at the bus station back in Indiana. Sam gets her phone number and says he'll call. He suspects that it's more than just coincidence that she's there in Chicago and sends Dean off to check up on her and the symbol while he keeps an eye on Meg.
The symbol turns out to be Zoroastrian and meant for summoning a particularly evil demon called a Daeava. Sam follows Meg to a warehouse and climbs up an elevator shaft to see her talking to some kind of spirit or demon. She mentions the brothers and leaves. Sam invesitgates, finding a demonic altar and a copy of the same symbol they found at Meredith's apartment.
He and Dean meet up and fill each other in on what they found. Dean tells Sam that both of the victims were born in Lawrence, Kansas. Realising that this could be related to the demon that killed their mother, they leave a message for their father asking for his help.
They both sneak into the warehouse but are spotted by Meg. They are attacked the daeva and tied up. Meg reveals that they were just the bait--the trap is actually for John. She knows that John has one weakness: that when it comes to the boys, he lets his guard down. Dean gets caught by her trying to escape, but she spots him. What she doesn't realise is that Dean was the distraction and Sam has managed to escape. Meg gets attacked the Daevas and is thrown out of the window, ending up dead on the sidewalk.
They return to their room and find John waiting there for them. He realised about the trap and stayed away from the warehouse. The demon knows he isclose to killing it and keeps trying to find ways to keep John away. Suddenly, the daeva attacks John and the boys, and we see that Meg is actually still alive, possibly still controlling the daeva.
Sam lights a flare to scare off the shadow demons and the three of them stumble out of the room. Outside, Dean tells John that he cant come with them. He explains that if the demon is using them to get to John, he needs to be away from them--he's stronger and less vulnerable when he's not with them. Reluctantly, they split up again and John drives away from his sons.