Each one focuses on one of the Doctors and apparently it all ties together at the end. I wouldn't know this because I haven't heard any of them. Eh they were alright stories on their own. The only "arc" was that the Eleventh Cocktor asked each incarnation for some shit that had been influential in the story, which is then poorly resolved in a finale more disappointing and convoluted than anything Steven Moffat has done (I'm serious. The defeat of the Big Bad goes something along the lines of "Doctor creates some mini paradoxes via the things so that some dude from the future that was born because 2 separate incarnations got his parents to do the dirty, travels back to 2013 and crushes the Big Bad." Yeah) Although I was probably high at the time I listened to this, so go and listen to it an