For those new to Spooks, it's a drama that's packed with twists and turns, clever characterisation, conspiracies and a generous dollop of intrigue. The Spooks of the title are counter-terrorism spies, living in a constant world of danger, and some of the edgy plotlines of this and the seasons that preceded it are testament to that.

After the minor criticisms levelled at season three, this fourth series jumps back into action, and while you won't find spoilers here, it quickly exceeds expectations. So when the credits roll at the end of the superb final episode, there are few who won't be checking out a release date for the fifth series.

Inevitable comparisons to 24 ensue, but the beauty of Spooks is that it has enough verve and enough ideas to carve out a niche all of its own. It's an excellent piece of British television drama, and while its tough approach won't engage with all, the majority are likely to find themselves hooked. And quickly. --Jon Foster