The Keys of Marinus is, quite frankly, a very good arc. The episodes follow one another, and I like this idea of a quest. Finally, the scenario is not long, and we can feel that the writers had fun. Report at trial, I don't know about you, I found it quite convincing. I was not bored watching this arc and I therefore award it the prize for the best rated classic arc of the moment with 4.5/5.