Two milestones occurred in Earthshock. Firstly, the Cybermen returned, unannounced, for the first time since Revenge of the Cybermen in 1975 with a completely different design, with David Banks' first appearance as Cyber-Leader, a role he would return to in subsequent stories involving the Cybermen until Silver Nemesis. Secondly, for the first time since The Daleks' Master Plan which had aired in 1965 and 1966, a companion died. Other milestones included Black Orchid, the first non-science fictional historical serial since 1966's The Highlanders, and the destruction of the Doctor's sonic screwdriver in The Visitation. A cliffhanger ending to the series appeared to have left Tegan stranded at Heathrow Airport with the Doctor abandoning her by mistake (the Doctor had spent most of the series trying to get Tegan back to Heathrow, which almost became a running theme).
Episode 1
Southern England, 1981. The universe has been saved, but at the cost of the fourth Doctor's life. The newly-regenerated fifth Doctor must rely on his friends to survive as the regeneration threatens to fail…
Episode 2
The TARDIS is plunging toward destruction. But even if the Doctor can escape, is yet another trap waiting?
Episode 3
The Doctor has arrived in the supposed safety of Castrovalva. But something is odd about the seemingly tranquil city…
Episode 4
The TARDIS crew are caught in a space-time trap. Escaping will mean a final confrontation with the Master.
Episode 5
Deep space, four days from Earth, 1981. The TARDIS materialises aboard a massive Urbankan starship. What is the real agenda of Monarch, master of the vessel?
Episode 6
The Doctor and his companions explore Monarch's vessel. But what is the secret of the ancient Earthlings aboard?
Episode 7
Bigon reveals Monarch's terrible plan to the Doctor. Can he act in time to save Nyssa? And which side is Adric on?
Episode 8
The Doctor has little time left to stop the evil Monarch. But he is losing allies — and the TARDIS is gone.
Episode 9
The TARDIS lands on the jungle planet Deva Loka, where an Earth expedition has been sent to study the Kinda, a tribe of primitive people. Three team members have already vanished. Are the Kinda as primitive as they seem?
Episode 10
Sanders meets Panna and Karuna who leave a lasting impression on him, while the Dukkha does the same on Tegan. When Hindle's breakdown begins, the Doctor and Todd are in danger.
Episode 11
Aris now carries the mark of the Mara and has gained voice, so Panna shows the Doctor and Todd exactly what the past, present and future hold for Deva Loka.
Episode 12
As the Mara finally breaks free of its dream dimension, the Kinda must do everything they can to contain it. Hindle's need to destroy everything and everyone is unstoppable.
Episode 13
As plague sweeps 17th century England, the Doctor discovers a more exotic threat at work - shipwrecked Terileptil convicts, intent on making the planet their own.
Episode 14
To rescue Tegan and Adric, captured and interrogated by the Terileptil fugitive leader, the Doctor must get past the locals under alien control and overcome Death (an android servant dressed up as The Grim Reaper).
Episode 15
The Doctor makes the fugitive Terileptils a rare offer they shouldn't refuse; but, though few in numbers, they have a plan in the works for the quick and complete domination of Earth and mean to see it through.
Episode 16
With Tegan and Richard under alien control, and the manor sealed against anyone leaving or entering, it's a question whether or not the Doctor can get to London before the Terileptils release their improved strain of black death upon the world.
Episode 17
The TARDIS arrives on Earth in 1925 where, due to a case of mistaken identity, the Doctor ends up playing in a local cricket match, but events take on a more sinister tone at the country home of their host Lord Cranleigh.
Episode 18
Ann escapes her Harlequin-clad abductor but it's The Doctor whom she accuses. Strangled bodies mount and The Doctor is arrested along with "accessories" Tegan, Nyssa and Adric. Will Lady Cranleigh's secret come out?
Episode 19
The TARDIS crew arrives on Earth in the 26th Century in a cave system where a military force is investigating the disappearance of a palaentological expedition.
Episode 20
With her crew vanishing mysteriously, Captain Briggs assumes the Doctor is the guilty party, but the traitor is closer to home… as are the Cybermen.
Episode 21
The Cybermen are released from their silos and are on the march, attacking Briggs's crew and ensuring that the freighter remains on course for Earth. But why?
Episode 22
The Doctor realises the freighter is now a huge bomb and sends it back through time where it can explode millions of years ago... but Adric is still aboard...
Episode 23
A Concorde loaded with passengers and crew vanishes into thin air. The still-grieving TARDIS crew arrive at Heathrow Airport in 1981 as the Doctor volunteers his services to solve the mystery.
Episode 24
The Doctor's TARDIS is stolen, and tracking it down reveals the existence of an alien named Kalid controlling events in the past. While the Doctor challenges Kalid's motives for being there, Tegan and Nyssa discover the source of Kalid's power - an even greater threat for the Doctor.
Episode 25
From within their sarcophagus, the gestalt Xeraphin are communicating through Nyssa. But their psychic energy is so powerful it may destroy her body completely.
Episode 26
The Master's TARDIS is repaired and the Doctor must follow him back to 20th century Heathrow, once he has rescued all the passengers and crew from both Concordes.