Claiming Earth in the Name of the Sontarans

UNIT has been given the task of investigating why several high-profile scientists have been mysteriously vanishing. The Brigadier has therefore decided to collect together all the top scientists into one top secret establishment making it easier for them to be protected by UNIT. It is there that The Doctor meets journalist Sarah Jane Smith, who has infiltrated the complex, so as to carry out her own investigation in the missing scientists, by posing as her aunt Lavinia Smith, a noted virologist.

When Sarah queries The Doctor she does not get very far. Worse still The Doctor reveals that he knows that Sarah is an imposter. But he realises that her presence will do no harm – especially as The Doctor is more concerned with getting a strange machine that he has built working. It is a rhondium sensor that he explains to Sarah will detect delta wave particles which when any are detected he will then wake him up. That night, the machine operates and one of the scientists, the eccentric and short sighted Professor Rubeish, vanishes from the security establishment. The Doctor uses another device to sweep the area and sees a ghost-like figure on the stairs. He hurries back to his TARDIS so that he can follow the trail left by the strange apparition. However, unknown to The Doctor during the disturbance Sarah has entered the TARDIS and so has unwittingly become a stowaway in The Doctor’s time-machine.

The ghost-like figure is in fact a Sontaran called Linx who has been kidnapping the scientists and transporting them back in time to the middle ages. The hypnotised scientists have then been put to work to repair his damaged spaceship. Linx’s spaceship had landed near a castle occupied by Captain Irongron, a robber baron, and his aide Bloodaxe. They were the first to discover Linx, and his spherical spaceship, in a nearby forest when investigating what they believed was a falling star. Linx needs Irongron's help to repair his ship and offers weapons in return. As the technology, at this time in Earth’s history, is primitive, Linx has had to gain scientific help from elsewhere – hence the kidnapping of the scientists from the Twentieth Century.

A Sontaran

The TARDIS arrives in Irongron's time and The Doctor sets off to locate the kidnapped scientists. Once he has left the area Sarah also exits from the TARDIS and starts to explore her new surroundings. Meanwhile, Irongron's behaviour has concerned his 'neighbours', Edward of Wessex, and his wife, Lady Eleanor. They therefore arrange for Hal, an archer, to shoot Irongron from his battlements. He is about to do just that when Sarah distracts his aim. The result of which ends up in both of them being captured by Irongron. Sarah, not realising that the TARDIS can travel in time as well as space, is not aware that she has been transported back in time. To explain the state Irongron's castle is in she convinces herself that it is part of a theme park or a film set.

Sarah though soon finds herself being interrogated by Linx who has recognised that she is wearing machine-woven clothes and so is not from this time period. Unable to obtain any meaningful information from Sarah the Sontaran then shows Irongron his new weapon, a fighting robot. This distraction allows Sarah to slip away. Unknown to anyone in the castle The Doctor has also arrived. When Hal is made to fight the robot The Doctor shoots the control unit from Irongron's hand with a crossbow. The ensuing confusion lets both Hal and Sarah flee and head for Wessex Castle.

The Doctor Meets Sarah Jane Smith

Even though The Doctor has realised that Sarah had stowed away in the TARDIS he is more concerned about discovering that Linx is a Sontaran and realises that he is supplying Irongron with weapons that are far more advanced for the century they are in. The Doctor finds Linx's workshop and discovers all the missing scientists in a state of extreme exhaustion. All are hypnotised except for Rubeish who escaped hypnotism due to his poor eyesight. Linx enters and The Doctor offers to help the Sontaran, as long as he stops supplying arms to Irongron, but Linx will not listen and stuns The Doctor with his gun. With The Doctor immobilised, Linx explains that he was with the Fifth Sontaran Army Space Fleet and that he had been attacked by Rutan fighters, while on a reconnaissance mission, and so forced to land on Earth. Linx then attaches The Doctor to a machine that delivers electric shocks if he tries to escape. However, Rubeish releases The Doctor when Linx has gone.

Meanwhile on reaching Wessex Castle Sarah is introduced to Edward of Wessex and Lady Eleanor. On learning of the trouble Irongron and his men have been creating she hatches a plan to kidnap The Doctor – believing that he is behind the scientific knowledge being gained by Irongron. She and Hal lead a raid on the castle and are able to capture The Doctor. Sarah though is shocked to discover the truth about The Doctor but once the misunderstanding is cleared up she helps The Doctor to defend Wessex Castle when Irongron's men attack. He and Sarah instruct Edward's men to construct dummies to place on the battlements and The Doctor makes some smoke bombs from saltpetre, sulphur and fat, together with some extras to provide a noxious smell. When Irongron's attack fails, and he and his men retreat back to their castle, Linx is unimpressed with the way Irongron carried out the attack.

As it is only a matter of time before Irongron attacks again, using more sophisticated weapons supplied by Linx, The Doctor proposes that they capture Irongron's castle. He therefore gives Lady Eleanor a list of ingredients to enable him to make a sleeping potion. A little bit latter, dressed as monks, The Doctor and Sarah get past the sentry guarding Irongron's castle. While The Doctor helps Rubeish and the other scientists, Sarah heads for the kitchens where she is found by Meg, the cook, and made to work preparing food. This though gives Sarah the ideal opportunity to pour the sleeping potion into the cooking pots.

A Ghost?

The Doctor, meanwhile, manages to break Linx's hypnosis by flashing a penlight to a polka rhythm in the scientists' eyes. Linx then arrives but The Doctor manages to keep him talking while Rubeish hits the Sontaran over his probic vent - a hole in the back of his neck - which stuns him. The Doctor then ties him up and then dresses as the robot to delay Irongron. His ruse though is soon discovered prompting Irongron to use The Doctor for target practice with his new guns. As The Doctor dodges the guns, Sarah comes to his rescue and the two of them return to Edward's castle to wait for the potion to take effect.

Having been unable to hit The Doctor with the guns Irongron goes looking for Linx and, on discovering the Sontaran tied up, releases him. Linx then completes the repairs to his ship and starts the power build up to take off. On returning to Irongron’s castle The Doctor, Sarah and Hal discover that everyone has succumbed to the sleeping potion. The Doctor uses an osmic projector, from Linx’s spaceship, to send the scientists back to the Twentieth Century while Hal goes to disarm Irongron's men but Irongron awakes and goes looking for Linx.

Linx though discovers The Doctor and they wrestle in combat. The Doctor is saved when a crazed and half drugged Irongron arrives and accuses Linx of betraying him. The Sontaran responds by killing him. As Linx enters his spaceship and prepares to leave, Hal arrives and shoots an arrow hitting the Sontaran in the probic vent. However, as Linx falls dead over his controls he triggers the launch mechanism. Knowing the place is about to explode when the spaceship takes off, The Doctor orders everyone to leave the castle. And so The Doctor, Sarah and Hal flee the castle just before it is destroyed. The Doctor and Sarah then depart in the TARDIS.