|We open at a psychiatric hospital. A woman is being asked why she hasn't been taking her meds. She says there is a monster coming and she doesn't want to be too sleepy to defend herself. She is told she is schizophrenic and that "there is no such thing as monsters."
That night, the same patient is in her room and hears something coming through her vent. She's screaming for help and another patient sees her through his window, but can't help. When they go into her room, her wrists are slashed -- looks like a suicide.
Dean and Sam go to the hospital, claiming to be referred by Dr. Babar. Dean is trying to check Sam into the hospital so they can investigate. Sam tells the doctor the truth -- he started the Apocalypse after killing Lilith. Of course, this does sound crazy to the doc. Then, Dean backs up the story and they are both committed to the hospital. Naturally, this was their plan all along… though they weren't expecting a body cavity search. D'oh!
They then run into Marvin, a mental patient and former hunter who can't handle his life hunting anymore. He is the one who called the boys. He's not sure if it's a demon, monster or what that's killing people at the hospital. Then, Sam is placed in group therapy, separate from Dean.
One of the patients in the group says a monster is hunting everyone in the hospital. The doctor is getting upset with the patient saying this. Meanwhile, a shrink meets with Dean. She's pretty, of course. They begin asking each other questions and her questions do hit a little close to home. Dean feels he's been raped… you know, mentally.
Then, some pretty blond walks up to Dean and begins making out with him. Presumably, she is a there for sex addiction. Sam says, "Dean, you CANNOT hit that." Next thing we know, screaming and the guy who was speaking earlier about monsters is found hanging in his room.
Next thing we know, Sam and Dean are performing a pseudo-autopsy on the poor guy. Sam actually saws the top of the guy's head off (ew!) and they find a shriveled up brain that has been sucked dry. Soon, one of the nurses finds the boys in the morgue, but don't catch them doing their investigating. Dean acts crazy by pulling down his pants as a diversion. (Hey, that would work on me!)
The team suspects they are dealing with a wraith that drinks the brain juice of crazy people. Wraiths can also pass as humans. Dean sees one of the doctors walk by and appear as a demon in a mirror. Bingo. They decide to go in after him and take care of the wraith. When Sam attacks, it turns out that the doc isn't the wraith after all. Good thing he didn't kill him.
Next, Sam is doped up and loving it. Dean apologizes for making the mistake and sets out to find the real wraith. Next thing we know, he's arguing with his pretty shrink in the hallway and it turns out that he's the only one who can see her! Now, Dean thinks he really might be going crazy. Or, maybe the wraith actually makes people insane. Maybe he and Sam were poisoned… perhaps by saliva? As in the pretty blond girl who keeps walking by and kissing the boys?
They go in search of the blond girl, only to find the nurse from the beginning of the episode who gave the boys their body cavity searches. She's the wraith and, well, obviously did more than search them earlier. She is sticking a needle in the blond girl's head and they stop her before she kills the girl. But now orderlies are after Dean, who is hallucinating wildly.
The evil wraith nurse goes to visit Sam in his padded cell. Just as she's about to kill Sam, Dean busts in and breaks off her evil, wraithy needle. It's gross, but the wraith is killed. As the boys try to make a run for it, an alarm sounds in the hospital.
They seem to make it to the Impala, but Sam is still breaking down. He thinks he's too angry inside. Dean tells him to bury it and keep going or else they really will end up nutso. Sam agrees to hang in there and they drive off.