Sam recovers from whatever it was and he's fine. They go to investigate two deaths. One is of a security guard killed at a school by an anatomy dummy. The other is a guy working at a mannequin factory and gets killed by faceless mannequins. Both kind of creepy. They figure out that a girl is missing and try to find a connection. She worked at the factory (like everyone else in town) and three guys played a prank on her and got her killed. The last guy is saved when Sam finds her body and burns the bones. He thinks that he's stopped her but he hadn't. She kills the guy in his apartment by possessing a creepy "girlfriend" mannequin. So Sam talks to the girl's sister to see if she has something of hers. Turns out she has a kidney that she got when she was 16. It's the kidney that is keeping the ghost around. So Sam and Dean try to figure out what to do and the ghost takes over the Impala. Dean gets chased and the sister ends up getting stabbed by flying glass and dies along with the ghost.
Also in this episode, Dean keeps getting calls from Lisa. He finally answers and it's Ben telling her something is wrong with Lisa and that she won't leave her room and he needs to come over. So that is how Sam ends up on this case by himself. Dean goes expecting the worst only to find Lisa is going a on a date. She's moved one. They have a heart to heart and she tells him she can't wait for him. Ben tells Dean he's being an idiot and that he doesn't care about family at all. So Dean leaves them.