Mulder and Scully arrive to help Skinner investigate the whistleblower's grotesque death. Skinner, who was just on the phone trying to placate an overbearing FBI superior, says there's "little time" and they're up against "one of the biggest corporations in America," Morley Tobacco. Tobacco is a multibillion-dollar industry and Morley is a big player.

Mulder comments that there are no ashtrays at the Scobie residence. But he also notices the odd black object in Scobie's drinking glass.

Dr. Voss's residence. A man walks out of the fog as the bearded scientist drives up. Voss is clearly unhappy to see him, and gives him several boxes of cigarettes. The man smokes.

The morgue. Scully does an autopsy and notes that Scobie died of oxygen deprivation. Although Mulder thinks it wasn't a homicide, tobacco beetles were involved.

Downtown Winston-Salem. The smoker who earlier met Voss watches a violent movie on TV in his apartment. His neighbor smells smoke through the vents and yells angrily through the wall. But the neighbor soon coughs up blood and drops to the floor with a thud. We see bugs crawling from his lifeless head.

Later, Skinner and the agents look at the corpse. Mulder again thinks this wasn't murder but rather the work of tobacco beetles. Could this be an insect-borne contagion? Mulder goes next door to see the smoker, whose name is Daryl Weaver. But Weaver wants to be paid and gives little information.

Scully contacts an entomologist to discuss the tobacco beetles. Mulder goes to see Voss at home. Voss says little, but seems conflicted. After Mulder leaves, the scientist gets a phone call from Brimley, the security chief, who was sitting in a car outside spying on the Voss residence. The company seems to care little for the privacy of its employees.

The entomologist tells the agents that these beetles have unusual mandibles and body segmentation. Scully thinks genetic engineering of the tobacco plant, upon which these beetles feed, is responsible.

Voss goes to Weaver's apartment, and, having emptied his bank account, gives the man $12,000 in cash. He begs Weaver to leave town, but only to be rebuffed.

After Voss leaves, we see Brimley lurking in the building.

The morgue. The autopsy of the last guy who died shows numerous beetle larvae in the lungs. Scully points this out to Mulder, but he just sits down silently -- and then starts coughing blood.

The hospital. Doctors give Mulder deep suction, a therapy normally used for asthma and cystic fibrosis. In this case, the goal is to remove beetle eggs from his lungs.

Morley headquarters. Skinner and others arrive with a search warrant. Over the unfriendly company lawyer's objections, Voss speaks. It was all an attempt to get a safer cigarette. Everything seemed to be going well -- the focus group enjoyed the new cigarette version. But then problems began.

There were four test subjects. Three died. (That's what Scobie, who was monitoring this focus group, was going to say in his testimony.) The fourth is still alive -- he is Daryl Weaver, whose ardent libertarianism ("E pluribus... whatever") fails to recognize the dangers of second-hand smoke.

And the smoke from the test cigarettes may carry the eggs of the deadly beetles.

The agents go to Weaver's apartment. They find Brimley, bound and gagged in a chair. They take off his gag -- and bugs come pouring out. Skinner watches with incredulous disgust.

Night. Weaver goes to a gas station and food mart. He bribes the clerk to allow him to smoke in the store, but doesn't buy cigarettes because they don't have his brand. When cops drive up, Weaver vanishes.

The hospital. Scully visits Mulder, who's awake but rasping. The he starts choking. The doctors storm in for a Code Blue emergency. A beetle shows up in Mulder's oxygen mask. Scully looks concerned.

Soon, she is behind the glass, looking pensive. A doctor wants to operate on Mulder, but Scully says that will kill him, so let's just wait. The doctor says just waiting will kill him.

The Voss residence. Skinner and some agents arrive and tell Mrs. Voss that the family needs protection. She's concerned. No one can reach Dr. Voss.

The tobacco lab. Skinner bursts in, gun drawn. Voss is sitting around, looking beaten and ill. He says "behind you," and Skinner turns to see Weaver, who has stolen some boxes of test cigarettes.

Weaver defies Skinner to shoot him, and states his understanding that Mulder's health depends on further research into why he, Weaver, has resistance to the beetle problem. So they need Weaver alive.

He lights a cigarette. Skinner shoots him. Then Skinner steps up to the wounded man -- and steps on the nearby lit cigarette.

The hospital. Mulder is recovering due to an infusion of a deadly insecticidal substance -- nicotine. But there's a new problem: He now craves cigarettes.

Scully is aghast, so Mulder throws his pack of Morleys (which look like Marlboros) into the trash. But after she leaves, he looks longingly at the wastebasket.