Digital Spy reports that one of the few former stars of Spooks (known in the US as MI-5) whose character managed to leave the series alive will return for the show's finale, which airs in the UK next week. The site couched their report in spoiler tags, so I won't reveal who (though fans can probably count the number of survivors on one hand, so it shouldn't be too hard to guess), but if you don't care about that you can find out by following the link here. I will say that the person in question is probably my favorite Spooks character (or second favorite after Harry), so I definitely welcome their return.
Read my review of MI-5: Volume 1
Read my review of MI-5: Volume 2
Read my review of MI-5: Volume 3