When he shoots at the creature, it flees. Pilot agrees to send out DRDs to track it down.

Meanwhile, since the DRDs haven’t found the critter, Pilot begins to worry that Crichton is hallucinating, especially after the hapless human sees Scorpius running through the corridor.

Some Farscape fans dream about this

Aeryn steps in some Vorc dung on the floor of her quarters, then confronts the creature itself sitting on her bed.

As she complains to D’Argo, the ugly little creature humps her leg. Then it picks up a scent and hurries out of the room.

Aeryn tries to follow, but loses it. It seems to be heading for the maintenance bay.

In the maintenance bay, meanwhile, a horrible monster has Chiana and Rygel cornered. D’Argo hurtles into the room. The creature knocks him down and runs.

Rygel crouches over the fallen D’Argo, explaining to the others that he’s clearing the Luxan’s airway. A minute or two later, D’Argo goes into convulsions.

They take him to the infirmary, and Zhaan tries to find out what’s wrong with him. "Try faster," Chiana frets.

Aeryn and Crichton continue the hunt, following a trail of crumbs to the Vorc. Crichton suggests using the Vorc as a bird dog to find the parasite, but it tries to bite him.

"I hate critters," he mutters, leaving the problem to Aeryn.

D’Argo is getting worse. Zhaan has figured out what’s wrong – he’s been poisoned.

DRDs on patrol

Crichton searches for the critter on Pilot’s scanners. To complicate things, Scorpius appears to him on the screen, saying "You will never see it coming, John."

Zhaan needs a venom sample to prepare an antidote, which means the creature will have to be captured alive. In the meantime, she’s using one of Moya’s neural clusters to stimulate D’Argo’s nervous system and prevent the venom from stopping his heart and lungs.

Rygel arrives to keep D’Argo company.

Elsewhere, Aeryn carries the Vorc around the ship on her back. It picks up a scent, leaping off her back and racing down the corridor.

The DRDs find the parasite in an airlock above the infirmary, but it gets past them. It heads for the command deck, now with Crichton, Aeryn and Chiana in pursuit.

They search the command deck. Crichton ends up finding the alleged vermin deterrent despite another brief vision of Scorpius.

"Show us the parasite," Aeryn tells it. The Vorc transforms into the horrible creature they’ve been chasing.

Scary monster go nap-nap

The crew promptly pelt the creature with sleep grenades and it collapses. They take it to Zhaan, who is dumbfounded to find that it doesn’t have any venom.

Crichton deduces that something else must have poisoned D’Argo. The Vorc simply has two forms – one for tracking parasites and a larger, stronger form for hunting them.

He wants to communicate with the Vorc, so they give it an injection of translator microbes. Unfortunately, the poor creature isn't quite smart enough to talk back, leading Aeryn to idly suggest killing and dissecting it -- at which point the Vorc demonstrates its understanding by loudly protesting.

"Take it back," Crichton tells her. Aeryn stammers out a painfully insincere apology.

Pilot reports that he can understand the creature. It doesn’t have a true language, but thanks to his experience in communicating with Moya he can decipher the basic concepts it is trying to express.

The Vorc says it wants to hunt the parasite. Crichton decides to trust it enough to let it go – but he warns it that he will shoot it if it makes one wrong move.

They begin the search again. Rygel is horrified to learn that they have released the creature, and threatens to kill it if it comes near him.

The Vorc gets the scent and takes off, transforming to battle form. It finds Rygel in the cargo bay.

"Kill it!" Rygel screams. Rygel and the Vorc struggle.

Aeryn and Crichton arrive, shooting. The Vorc flees and Rygel collapses.

And they wonder why they can’t get health insurance

Rygel is going into shock, leading Zhaan to believe that she made a mistake and the Vorc is somehow poisonous after all.

Still afflicted with occasional visions of Scorpius, Crichton sets out to capture it again. At one point, the leering hallucinations cause him to almost shoot Aeryn.

He and Aeryn follow a trail of blood through Moya while the critter skitters down a corridor behind them. It seems to be leading them back to the cargo bay.

Crichton and Aeryn suspect a trap. They come in shooting, hitting the creature several times.

"What is that?" Crichton asks. A black cocoon has been glued to the side of one of the cargo containers.

In the infirmary, Rygel shudders. Something crawls on his face.

Crichton realizes that the Vorc led them to the cargo bay so they could see the cocoon. The creature tears the cocoon open, revealing Rygel.

The "Rygel" in the infirmary sits up and stares at Zhaan.

Still trapped in the cocoon, Rygel explains that the creature grabbed him, taking his memories and imitating his form.

"How do I know you’re Rygel?" Crichton demands.

The Hynerian produces a prodigious flatulent display. Convinced, Crichton and Aeryn run for the infirmary.

An economy-size can of Raid

"Rygel" attacks Zhaan. Crichton and Aeryn arrive just in time to pull it off, throw it in a corner and blast it.

The creature staggers, breaks up into hundreds of vicious little bugs, and rushes the crew.

"Cover me," Crichton shouts. He tosses Aeryn his gun, then pulls out a tank of coolant and sprays the bugs while she shoots them.

Meanwhile, the Vorc is dying from the wounds Crichton and Aeryn inflicted. Aeryn tearfully apologizes to it. It forgives her and dies.

Head games

Crichton returns to his chessboard. Aeryn confronts him about almost blowing her head off during the search.

"What were you firing at?" she asks, and Crichton tells her about his hallucinations.

"It’s like he’s talking to me," he says. He promises to ask if he needs help, "just like you do."

She leaves. Crichton looks across the board to see Scorpius.

"When the trap closes," Scorpius tells him, "it’ll be too late."

"You think?" Crichton asks. He checkmates the enemy king.

Scorpius resigns the game, laying the king on its side. "That wasn’t the trap I meant," he says.

Crichton stares into empty space.