Yes, I am a little late on this one. Jekyll is a 6-episode series that aired on the BBC in June and July 2007. It is a continuation of The Strange Case of Dr. Jekyll and Mr. Hyde novella by Robert Louis Stevenson. A brilliantly cast James Nesbitt stars as Tom Jackman/"Billy" Hyde. Alongside him are Michelle Ryan (who was in the Bionic Woman remake), Gina Bellman, Meera Syal, Paterson Joseph and Denis Lawson.
At first, I didn't know what to make of the show. A friend recommended my husband and I rent it so we did. By the end of the first episode, I was hooked. I had heard it was like the Showtime series Dexter, however, I don't agree with that. (Though, I should note that I've only ever seen one episode of Dexter.) In my opinion, it's more like My Own Worst Enemy but a lot more maniacal. I don't want to say too much without giving away the major plot points but this is definitely something you should watch. And since it's only 6 episodes long, it really is easy to watch in one afternoon.