Arc of Infinity

Shielded by a collapsed star, lurks a malevolent presence, an alien consisting of pure anti-matter.  Its intention?  To bond with a Time Lord and so cross over into this dimension through the Arc of Infinity-the gateway to all dimensions.  Suddenly, the Doctor finds himself under attack and the TARDIS recalled to Gallifrey where he is put under sentence of death by the High Council of Timelords, for the bonding must be prevented at all costs.  Once there, the mystery deepens. 

How could the alien have gained the vital biodata extract necessary to carry out the bonding?  Is there a traitor amidst the Timelords?  What is the link between the alien and Tegan’s cousin’s disappearance in Amsterdam?  Just what is the identity of the shadowy alien-have he and the Doctor met before?  The Doctor must find the answers-and quickly. It is not just his life at risk. If the bonding is completed, it could cause the collision of matter and anti-matter and the destruction of all dimensions…

• "Arc of Infinity" begins the 20th anniversary of Doctor Who.  Each story within this season features the return of one of the Doctor's former adversaries.

• This adventure marks the return of Omega, last seen in the 10th anniversary story "The Three Doctors."

• Michael Gough guest stars as the Time Lord Hedin.  Fans may remember him as the Celestial Toymaker in the Hartnell classic "The Celestial Toymaker." 

• Tegan, written out of the final story of the previous season, is returned back to the TARDIS crew by the end of this adventure.

• Watch closely for Commander Maxil.  He is played by none other than Colin Baker (who would later go on and take the role of the Doctor the following year).