there is no arc.
http://www.guardian.co.uk/tv-and-radio/tvandradioblog/2012/aug/15/doctor-who-asylum-of-the-daleks
The big line with this series is "movie poster". They've realised that quite wonderfully with the pre-publicity, a poster which indulges the sci-fi show's finest B-movie traditions: the Doctor, Amy and Rory reflected in the eye-stalk of one of Skaro's worst. And while the movie poster line is meant to mean "blockbuster of the week", what it also means is "no two-parters" and "no series long story arc".
That will delight those who found last year's River Song saga too overwrought, but its actual thrill lies somewhere else. It's usually a back-handed compliment to say something was short yet felt long. But that wasn't what was going on here either.
Introducing the Asylum, BBC drama boss Ben Stephenson said that this series was a Hollywood movie each week. Afterwards, Moffat told me that the intention here is compressed storytelling – 90 minutes squeezed into 45. Actually, Asylum Of The Daleks manages to do a lot more than most of the classic series four-parters. It certainly manages to do more than, say, last year's The Rebel Flesh two-parter.
http://www.guardian.co.uk/tv-and-radio/tvandradioblog/2012/aug/15/doctor-who-asylum-of-the-daleks