The opening of Supernatural 4x06, "Yellow Fever," is one of my favorite episode teasers. We see the shadow of a man running and we hear his frantic gasps. Episodes of Supernatural almost always start with a victim of the week. The joke here is that when the camera pulls back, we see that the fleeing man is none other than Dean Winchester (Jensen Ackles), badass hunter. What he's running from is a little Yorkie. Okay, something wacky is going on this week.

What makes the joke work even better is the undercurrent of creepiness. The audio has deep-throated barking, the same barking the show uses for the hellhounds that mauled Dean at the end of season 3. The teaser sets up the way the episode works its tension. "Yellow Fever" is a hilarious episode – thanks in large part to Jensen Ackles' performance – with disturbing undercurrents.

Cut to 43 hours earlier. Sam (Jared Padalecki) and Dean are in Rock Ridge, Colorado to investigate a suspicious heart attack death. Posing as FBI agents, the boys watch the autopsy. Dean holds the heart and Sam gets splattered with spleen juice. The victim was a healthy man in his 40's, and there are mysterious deep scratches on his lower arms. Sam and Dean talk to the sheriff, who was friends with the deceased. The sheriff says Frank "was a good man," but he was acting oddly before he died, nervous and reclusive. The sheriff himself is acting oddly, or he just has a cold or he's a hypochondriac – he seems to have an over-fondness for anti-bacterial hand gel, and coughs a lot.

The weirdness with Dean begins when he nervously insists he and Sam cross the street to avoid a group of teenagers. They go talk to Frank's neighbor, who has a lot of snakes and reptiles for pets. He reveals that in high school Frank was "a dick," but in adulthood was a lot nicer. Frank's wife died 20 years ago, and he was devastated. During the conversation, one of the neighbors' snakes slithers over Dean, who looks freaked out, but Dean doesn't like rats, either. And who wouldn't freak out with a large snake sliding over them?

But when we next see the boys, Dean is scratching at his arm. He drives the Impala timidly within the speed limit. The EMF meter in Sam's pocket goes off – turns out it's taking readings off Dean. The next morning, Sam says he talked to Bobby and they have a theory about what's going on. It's a ghost sickness, a disease where the dead can infect the living, and Sam says it spreads like a cold or flu. Dean asks why he's infected and Sam isn't – after all, Sam got splattered by spleen juice.

Sam: Turns out all three victims share a certain personality type. Frank was a bully, the other two victims, one was a vice-principal, one was a bouncer. Basically they were all dicks.
Dean: So you're saying I'm a dick?
Sam: No, it's not just that. All three victims used fear as a weapon.

The connection between Dean and the victims as laid out here seems a little murky, but it never seemed to me that the episode meant that "Dean is a dick" was the explanation. We know from season two's "Croatoan" that Sam is immune to demon viruses – maybe he's immune to a ghost virus as well. It's hard to tell if the show remembers that, and Sam may be lying because he doesn't want his demon blood to be a topic of discussion, or if we're meant to think it's because Dean uses violence in his work – he scares scary things. Sam and Dean both acknowledge here that they often scare people; and Sam and Dean both have had their moments of obnoxious behavior. In the context of the episode as a whole, and somewhat less clearly even in this scene by itself, I think it comes across that "Dean is a dick" was not the reason he got the ghost sickness (more on that towards the end of the review).

Dean waits alone for Sam to return to the motel room, and the sequence is both funny, affecting, and disturbing, as a clock on the wall irritates Dean and he hallucinates the words in the book he's studying mocking him: "You're dying…again…loser." Jensen Ackles' performance as he shows us Dean's gradual breakdown, and Dean's struggle to keep it together, is wonderful.

Jared Padalecki also turns in a strong performance as Sam. The younger brother and traditionally the protected one, Sam has to remain calm to look after Dean and solve the mystery before his brother dies again. Sam seems almost too calm, which fits with how in Season 4 so far, it seems as if Jared Padalecki is playing Sam as a little bit emotionally numb. Jared Padalecki walks a fine line in this episode – we see flashes of his concern for Dean but mostly he seems mildly annoyed, and it's a big contrast to how we've seen Sam behave in the past when Dean was in peril. We know Dean's death was traumatic for Sam, and we don't know much yet about those four months when Sam hunted alone. It's also possible it was just intended to be a light episode, without a lot of brotherly drama -- although given the dark content of its ghost story, and the hallucination Dean has about Sam, that seems unlikely.

Dean coughs up a wood chip, which turns out to be from the spirit infecting Dean. Sam says Dean himself is the best clue they have. "I don't want to be a clue!" Dean protests. The boys go to the local sawmill, as Dean's condition worsens, to the point where he refuses to carry a gun because "it could go off." He chooses flashlight duty instead, shrieks at the sight of a cat, and flees when the ghost of a man murdered 20 years ago appears. It turns out this is the ghost infecting Dean and the other recent victims, causing their bodies to represent his death.

Sam and Dean interview the man's brother, who tells them the deceased was a gentle person, a socially awkward giant of a man, feared and misunderstood. The man, Luther, also had a crush on Frank's wife Jessie. Meanwhile, the sheriff is starting to unravel, infected by the ghost disease himself. It turns out Jessie was an unhappy woman who killed herself, but when she vanished, Frank suspected Luther and brutally road-hauled him. The sheriff knew and covered it up. Luther's ghost is now infecting people, seeking justice.

Dean's rant about hunting brings us to right before Dean runs off to be menaced by the Yorkie. Again, the scene is both funny and poignant, and on a certain level, true – not only about the annoyances of working with family and the down side of life on the road, but about the weirdness of hunting. "Normal people, they see monsters and they run," Dean complains. "But us? We search out things that want to kill us. Or eat us! You know who does that? Crazy people! We are insane!" I also love Sam's reactions to Dean's rant; he seems both patient and mildly alarmed, willing to let Dean get it out of his system and hoping things don't get any wackier, ready to act if they do.

The real pay-off in the episode, and when the darker undercurrents come to the front, is when Dean confesses his despair to Sam that he's dying and Sam first reacts coldly, and then his eyes flash yellow and he tries to strangle Dean. This is Dean's worst fears manifest, not only that Sam finds him an annoyance, but that Sam will go evil. The real Sam pulls Dean out of the hallucination.

Picking up on the theme of people who use fear as a weapon, Bobby (Jim Beaver) and Sam's solution to purge the ghost seems brutal in itself, a fact Sam himself acknowledges at the end of the episode. They can't do a salt and burn because the remains are too scattered. Instead they use a spell and an iron chain to road-haul Luther's spirit, scaring the ghost out of existence by reenacting his death.

Meanwhile, Dean tries to hold it together back at the motel, but finally crumbles. The sheriff, caught in full-blown insanity himself, shows up to kill Dean, and dies of a heart attack. Traumatized, Dean grabs a Bible as his hallucinations worsen, significant considering his interaction with the angel Castiel. It seems more likely Dean is grabbing at any port in a storm than that he's finally found faith, but maybe Dean is closer to viewing God as a comfort. Or he's hoping Castiel can save him again.

Dean hallucinates the demon Lilith, who held his hell contract and appears as the little girl she last possessed. Her mocking – created by Dean's own mind – pushes Dean's heart to the maximum and only Sam and Bobby's actions at the sawmill save him. Dean's hallucination Lilith says that four months on earth was forty years in hell and that Dean remembers all of it. When Dean asks her "why was I infected?" she says "you know why, Dean. Listen to your heart."

Which suggests the exposition we got on why Dean caught the ghost sickness definitely wasn't the full explanation. I felt as if this came across in the episode itself, even before executive producer Eric Kripke's statement (warning: he drops a spoiler for an upcoming episode) clarifying the exposition scene. He made the statement after a number of fans on message boards objected -- for some viewers, the episode came across as saying that Dean caught the ghost sickness because of dickish behavior. But the dialogue itself backpedals from that, and we have Lilith's hint. Also, on genre TV series, characters do odd or puzzling things, and a few episodes later we find out what's going on, it's part of the mystery. It raises the question, how much should showrunners explain? There have been episodes of Supernatural more problematic and controversial than this one.

The final shot of Dean and Sam leaning against the Impala drinking beer, with Dean fully recovered and back to his own relative state of normal, is beautifully filmed. It's a peaceful moment between the boys – until Sam's eyes flash yellow, just for a second. The moment emphasizes that Dean's fears about Sam are still there, even without a ghost sickness to bring them out.

Overall, an effective if somewhat wobbly episode with a lot to think about.

Episode 4x06, "Yellow Fever"
Writer: Daniel Loflin and Andrew Dabb
Director: Phil Sgriccia
Guest stars: Jack Conley, Sierra McCormick, Stephen Duvall

Source:
TVguide.com