But Tegan, once again a member of the TARDIS crew, is not her own boss. An unsuspecting medium for the sinister Mara, she enables the evil exile to return to is home planet.

On Manussa the ten-yearly celebration of the Mara's banishment is about to take place. Only the Doctor realises that this could in fact mark the spectacular revival of a reign of terror - but no one will heed his warning.
 

"We're not supposed to be here....."

Surely Tegan must have made a mistake when she set the TARDIS' co-ordinates, because the Doctor certainly hadn't intended landing on Manussa? But upon learning that Manussa was once home to the Sumaran Empire, the Doctor knows that their arrival has been no accident but has been orchestrated by a hostile force - a force which is rapidly gaining control of Tegan's will.

By first infiltrating Tegan's subconscious mind, through strange and disturbing dreams dominated by the image of a huge snake's skull, this force - 'The Mara' - is planning on using Tegan as a vehicle for its return to power on the planet Manussa.

So just as Manussa prepares festivities to commemorate the destruction of the Sumaran Empire by the ruling Federation, it seems that the Legend of the Mara could be about to come true. According to this legend, the Mara was never destroyed by the Federation but merely banished. Furthermore, the Legend claims that the Mara will return in a dream - a precursor to its gaining control of all their minds..

It is clear to the Doctor that the first steps in the Mara's return have already been taken...

Running Time: 98 mins approx

Originally transmitted: 18-26 January 1983 
Produced by John Nathan-Turner, Directed by Fiona Cumming