I think the episodes with The Doctor (Tom Baker) and Leela (louise Jameson) are the best. This is classic Doctor Who in terms of arriving - he knows not where - and immediately becoming in a local issue of wrongdoing, which he must rectify.
This one of the best stories in terms of sic/fi concepts and character interactions. I love Tom Baker and Louise Jameson,so this is a favorite. Great suspense as the Doctor appears to align himself with the enemies of Time and Gallifry.