Farscape - Season 4

Crichton, who is now aboard a dying Leviathan named Elack, works on his theories of wormhole physics. But when a female alien named Sikozu lands on the ship, she is followed by a squad of Grudek mercenaries who want to harvest the Leviathan's neural cluster tissue. Crichton struggles to save his new home but gets some welcome help when two old friends rejoin him.

Elack arrives at a planet and Crichton, Chiana and Rygel are reunited with D'Argo and Jool who are at an archaeological site run by Jool's people, the Interions. The purpose of the dig is to find a missing probe which might reverse the dangerous atmosphere of the planet. But things take a turn for the worse when Peacekeepers led by Grayza land on the planet.

When D'Argo and Sikozu come up with a plan to crash Elack (the dying Leviathan) into the Peacekeeper pursuit craft, Crichton is forced to get closer with Grayza to ensure the success of the plan. But when the plan goes wrong Crichton and the rest of the crew are forced to go looking for the third probe to end the magnetic summer forever.

While the crew has stopped off on a planet, Rygel leaves the rest of the group and is caught in an unbreakable orange substance as he's stealing treasures he discovers in a cave. When D'Argo, Crichton and Noranti go looking for Rygel, the cave seals them in. Two huge grunts appear who have protective armor which protects them from weapons fires.

D'Argo, Rygel, Crichton, Chiana and Sikozu get back to Moya, only to find that Scorpius is there waiting for them along with Aeryn, now suffering from heat delirium. Aeryn has granted Scorpius asylum and claims that Scorpius saved her life.

While in close proximity to a wormhole, Moya is preoccupied and doesn't notice a slowly moving object heading towards her. Moya collides with the object which then covers her entire hull, causing great discomfort to her as well as the crew.

While on a transport pod, Chiana nags Crichton to try out a virtual reality game. A transmission comes through from D'Argo concerning a problem with Scorpius. Despite this, Chiana pulls Crichton into one of the games, where they become trapped., and the only way out is to complete the game.

A group of bounty hunters come aboard Moya and take everyone hostage. When Crichton arrives back with Noranti, he destroys the bounty hunter's ship and goes aboard Moya to rescue everyone whilst Noranti puts herself into a coma so she can survive outside the ship.

With Moya immobilized in Tormented Space, Crichton, Aeryn, Chiana, D'Argo and Sikozu seek temporary respite on a planet inhabited by historically warring clans who are now experiencing a fragile peace. The crew's arrival coincides with preparations for the election of a new ruler, or 'Prefect'. Incumbent Prefect Falaak is at the end of his half cycle in power, and reluctant to concede it. Popular clan leader Gashaah looks the likely successor, but faces a strong challenge from the Chieftan of the Jabuka Clan.

Aeryn begins experiencing strange hallucinations, then without warning opens fire upon a meeting of the clans; when it is over, Gaashah lies amongst the dead, D'Argo wounded. She escapes during the confusion, leaving her crewmates under suspicion.

The crew consume food, sharing amongst themselves, unaware that if these special mollusks are not ingested by the same person, it becomes toxic. Consequently, they must quickly find a cure or they'll die. Fortunately there's someone who's happy to come through... for a price. But there's more going on here than their own problems, and solving them may be a real drag!

Crichton gets sucked into a wormhole while he is studying it, but instead of exiting the wormhole on the other end he becomes trapped with a mysterious man inside the wormhole. The man claims he is a relation of The Ancients who Crichton met before and gave him his wormhole technology. He demonstrates the consequences of wormhole travel to Crichton and forces him to confront the possibility that he may never be able to get home.

After accidentally returning to Earth, Crichton discovers it he is in 1985 and he has altered the time line, causing his father to be scheduled to fly on the doomed shuttle Challenger.

Moya arrives at Earth in present day, Christmas. The crew show their ships and technology to Earth's scientists. Crichton starts writing a journal. The creature left onboard Moya by Grayza manages to get to Earth where it starts killing and hunting down Crichton.

Moya takes on a new passenger when Chiana insists that they rescue the young female from the men exploiting her. However, they soon learn that Talikaa is not the innocent that she pretends to be, but rather an alien predator in disguise who plans to feed on their neural energy.

Scorpius signs D'Argo, Crichton and Rygel up for a training camp where the students learn mental discipline by battling in an artificial environment.

At a commerce settlement, Aeryn, Chiana, Noranti and Sikozu make a deal for a sensor distorter to shield Moya from detection. Construction will take time, though... leaving them stuck there just as Peacekeepers and Scarrans arrive for a secret diplomatic meeting. As Chiana and Noranti try to avoid detection, Aeryn and Sikozu do some spying. Grayza makes the Scarrans a surprising offer to ensure peace... endangering many innocent lives in the process. War Minister Ahkna has some surprises of her own... forcing Aeryn and Sikozu to take action.

Crichton watches a documentary that Moya receives from Earth about their recent visit showing interviews with Crichton's relatives and other people who interacted with the crew.

Crichton and Scorpius travel to one of the 'unrealized realities' where Crichton believes he heard Stark say "Katratzi". Meanwhile on a Scarran ship, Aeryn resists torture, while protecting herself and her and Crichton's child.

Moya arrives at a station where the Scarran vessel transporting Aeryn is docked.

Moya arrives at Katratzi. Crichton attends the peace talks between the Scarrans and the Peacekeepers... with a nuclear bomb.

The plan to rescue Scorpius from Katratzi fails and all because of the hybrid himself. He claims it was for the crew's own good, but, regardless, they are now stuck. Most still want to find another way out, but Scorpius reveals some secrets and pushes a plan to strike a major blow against the Scarrans. His target, surprisingly, is the Crystherium Utilia. The crew had better hurry, especially once the Scarrans deactivate Crichton's bomb. Success ends up depending on a secret held by Sikozu. Elsewhere on Katratzi, Rygel and Noranti search for Stark, only to run afoul of his bioloid. Meanwhile, Grayza fears her plans for peace have failed and now threatens to ignite a war.

With their Crystherium stores low, the Scarrans must travel to Earth through a wormhole to replenish their supply, as those flowers grow there. With Pilot's help, Crichton tries to collapse the wormhole leading back to Earth.