The Doctor's trial continues. The Valeyard's next piece of evidence for the prosecution concerns the Doctor's recent trip to Thoros Beta. Though originally investigating arms dealing, the Doctor and Peri become embroiled in their old enemy Sil's alarming neurological experiments...
Elenco: William Hartnell , Patrick Troughton , Jon Pertwee , Tom Baker , Peter Davison , Colin Baker , Sylvester McCoy .