The Doctor and Romana

Travelling through E-Space, the TARDIS is hijacked by a time sensitive Tharil named Biroc. Biroc phases into the TARDIS, which has become trapped in a time rift, and operates the controls. The TARDIS then materialises in a white void at the centre of the Time Lines.

Biroc is the imprisoned navigator of a ship, The Privateer, that is captained by Rorvik, and which is also trapped in the void. The Privateer is carrying many of his Tharil brothers into slavery as time-sensitive navigators and he has brought the TARDIS to the void so that his race can be rescued.

On arriving in the void Biroc warns The Doctor, Romana, Adric and K9 that he is a shadow of his own past - and of their future - and that the others that are following him should not be trusted.

Biroc and The Doctor

Leaving Romana and Adric worried about K9, whose memory wafers have been shredded by the time winds, the Tharil disappears with The Doctor in pursuit. The Doctor follows the image of Biroc through the void to a strange stone gateway, which leads to a decrepit, dusty and deserted banqueting hall which is still laid for a meal.

Biroc disappears into a mirror as The Doctor watches and time begins to jump about as The Doctor finds himself back in a period when the hall was occupied. This is the domain of the Tharils, who in a previous time were cruel masters to their human slaves but have now repented.

Rorvik

Biroc explains about his mission to free the Tharils, but then their meal is interrupted by Gundan robots, creations of the Tharils’ humanoid slaves, who in turn enslaved the Tharils and so led to their downfall. The Tharils though have realised the error of their formerly dictatorial ways and are now intent on escaping to continue their lives in peace.

But the void is shrinking and The Doctor deduces correctly that the The Privateer, which is made of Dwarf star alloy, is the cause of the problem and - more worryingly - there is not much time before the void retracts into nothing.

Rorvik, though is trying to break through the Gateway, and thereby gain access to N-Space. The insane commander intends to use a vast portable cannon on the Gateway and the mirrors in an effort to escape the void. Adric, who has hidden himself inside the cannon uses it to free The Doctor and Romana from the Gateway where they have become trapped by the slavers.

Romana and Adric

When the slavers set out in pursuit of The Doctor and Romana they find The Privateer is now much closer to the Gateway so proving that the void is shrinking and therefore doomed.

In frustration Rorvik fires the cannon at the mirrors, but succeeds only in destroying the weapon. This only enrages him further and the crazed and infuriated slaver now decides to use The Privateer’s engines to blast through the mirrors and escape the void. Instead, the mirrors reflect the blast back, and The Privateer is destroyed. Rorvik and all his crew are killed but the enslaved Tharils are freed and so are able to travel back through the Gateway.

Romana, who has formed an empathy with the Tharil race, elects to travel through the Gateway with them and help liberate the remainder of their race. The Doctor gives her K9, who will be restored beyond the Gateway, though he can never return.

After Romana and K9 depart, The Doctor uses the knowledge he has gained from the Tharils to successfully pilot the TARDIS - now occupied only by himself and Adric - through the Gateway and back into N-Space.