A mysterious explosion has knocked the TARDIS into void. And in their confusion, the crew are turning on one another.

The TARDIS is adrift, the crew turning on each other. Only by working together can they find their way out before they are destroyed.

The TARDIS lands in the Holy Land during the Third Crusade and the crew help save Richard the Lionheart from an ambush, but Barbara is captured and brought before Saladin.

While the Doctor, Ian, and Vicki are drawn into the intrigues of King Richard's court, Barbara has to cope with an impatient Saladin and the vengeful El Akir.

Barbara allies herself with a man whose were murdered by El Akir as the Doctor and Vicki are caught up in Richard's plan to offer his sister's hand in marriage to Saladin's brother.

Ian sets out with a reluctant accomplice to rescue Barbara from El Akir's palace as the Doctor and Vicki try to evade the suspicions of the Earl of Leicester.

With Bragen having taken over, the Daleks trick the rebels into turning them loose and only the Doctor can stop them wiping out the entire colony.

The Doctor and Jamie investigate Waterfield's antiques shop, where they are knocked unconscious and transported back to the 19th century.

As part of the Daleks' experiment, the Doctor manipulates Jamie into attempting to rescue Victoria.

Jamie and Kemel team up to try and find Victoria, while the Doctor and the Daleks continue to monitor their progress.

With the experiment at an end, the Doctor begins to suspect the key to rescuing Jamie, Victoria and Kemel from the Daleks lies with Terrall.

The Doctor, Jamie and Waterfield follow the Daleks to Skaro, where they discover an unforeseen consequence to their experiment.

The Daleks are poised to spread the Dalek Factor throughout the history of Earth and begin by implanting the Doctor.

After the Doctor is attacked by a group of mysterious gunmen, he discovers he is the physical double of the famous scientist Salamander.

Jamie and Victoria agree to accompany Astrid to Hungary to observe Salamander's activities.

Jamie and Victoria join Astrid into attempting to rescue Denes but Salamander becomes suspicious of them.

The Doctor persuades Bruce to help him infiltrate Salamander's research centre while Salamander takes drastic action to prevent Swann finding out the truth.

The Doctor discovers the true link between Salamander and Kent while Astrid tries to convince the shelter inhabitants they have been lied to.

The Doctor and Jamie arrive on a mysterious spacecraft whose only occupant is a dangerous Servo Robot.

The Doctor and Jamie are brought aboard the Wheel where Jamie is horrified to learn the crew plan to destroy the Silver Carrier with the TARDIS on board.

Jamie sabotages the Wheel's x-ray laser, unknowingly giving the Cybermen an opportunity to reach the Wheel.

The Cybermen instruct their human slaves to smuggle them onto the Wheel while the Doctor attempts to convince Bennett of the threat they pose.

The Cybermen gain control of more members of the Wheel crew and the Doctor realises the only way to stop them is for Jamie and Zoe to make a dangerous space walk.

Jamie and Zoe attempt to recover the time vector generator while the Cybermen realise the Doctor is on the Wheel and make him their prime target.

While the Brigadier investigates a loss of contact with Mars Probe 7, the Doctor realises signals coming from the probe are of extra-terrestrial origin.

UNIT retrieve the returned Recovery 7 but then Carrington hijacks it while the Doctor and Liz try to decode the signal he sent.

Carrington is holding the astronauts at a secret location but when he takes the Doctor, Liz and the Brigadier there they find they have been kidnapped.

Liz has been captured by Reegan's men and the Doctor begins to suspect Taltalian is more involved than he appeared.

The Doctor decides to take Recovery 7 back into space to search for the missing astronauts but Reegan sabotages the launch.

The Doctor speaks with the alien captain and learns the astronauts sent to Earth were ambassadors. However, before he can alert the authorities he is kidnapped by Reegan.

Carrington is planning to expose the aliens on live television and call for an interplanetary war and the Brigadier must rescue the Doctor and Liz in time to stop him.