Favorite Episode?

[Nitrus]

What was your favorite episode of Series 4, and why?

Mine would have to be either The Book, or Divided They Fall (the british way one).

I loved the book because it had the conspiracy edge to it, and it was the introduction of Jo, which was done very well. It showed a non-spooks perception of what was going on.

I loved Divided They Fall, because they were trying to bring down the party from the inside, and it was done very well. The episode felt like it could really happen, or perhaps it already has happened. lol.

So what's your favorite episode from Series 4?