Series 4

Dorian, owner of the spaceship Scorpio, rescues the crew from Terminal. He tries to enlist the help of Orac to build a teleport mechanism for Scorpio and attempts to kill the crew.

The Scorpio, rendered inaccessible by an elaborate security system, is stolen by a native of the planet who seeks to escape. Avon completes the Scorpio teleport system with the help of Orac.

The planet Helotrix is falling easily to attack from a new Federation pacification drug, as are many other star systems. Tarrant and Dayna teleport down to the surface to investigate. Servalan, deposed of her presidency in the Federation, is back under the alias Commissioner Sleer having wiped all records connecting herself with the identity of Servalan.

After attempts to match the course of an asteroid for cover result in collision with the asteroid and severe damage to Scorpio's engines, the crew search for an experimental stardrive developed by an ex-Federation designer who is now working for a terrorist group.

Dayna meets an old friend, Justin, to seek help with synthesizing an antidote to the Federation pacification drug. Servalan learns of Scorpio's visit to Justin's planet and of the genetic research he is performing there.

The crew rescue a protege of Ensor's who instead turns out to be his android creation seeking to unite with Orac.

Servalan hires an assassin to kill the crew by luring them to a trap set aboard the assassin's ship.

The scientist Belkov has stripped a planet of a valuable crystalline substance and tries to double cross both Servalan and the Scorpio crew in an attempt to escape with the private stash he has collected. He is aided by his computer, an amalgamation of a standard Federation computer and a pleasure planet gaming machine.

Servalan investigates a planet which contains an unknown substance of potential usefulness whose investigation team mysteriously died. The crew learn of Servalan's trip and decide to investigate for themselves.

A plan to steal a shipment of atomically converted gold being transported from the planet Xeroc aboard a domestic passenger ship winds up turning into a major loss for the crew.

The scientist Egrorian offers Avon a powerful weapon, the Tachyon Funnel, in exchange for Orac. Servalan, who is behind the transfer, prepares a plan to double-cross Avon that would give her both the Tachyon Funnel and Orac.

Avon tries to form an alliance to produce an anti-pacification drug by negotiating with the leaders of three warring star systems. The Xenon base is sabotaged by explosives and a deadly virus. Tarrant falls in love with the daughter of the saboteur.

After Orac traces Blake's trail to the planet Gauda Prime, Avon and crew travel there, leaving the destroyed Xenon base behind. Scorpio is attacked on approach to the planet and crash lands on the surface of Gauda Prime. Avon and crew travel in search of Blake, and discover that he may have sold out to the Federation.