Hmm. I’m not entirely sure what to make of this week’s offering- I’m afraid you’ll have to bear with me for a bit whilst I scuttle around in the hope of formulating an opinion.

"You're not you" is one of the oldest tricks in the book, and one of the best. It's perfectly suited to Russell T Davies "domestic" approach to Doctor Who, allowing ordinary people's lives to be turned upside down by alien involvement. James Moran manages to include a number of variants on this theme within the space of the episode, from the initial suspicion of Beth and her partner, to her horror when confronted with the truth and guilt at her boyfriend's fate. The pace is furious, with the logical escalation of events one of the episode's highlights, as Torchwood's probing forces their opponents to play their hand. Also laudable is the thoroughness with which Beth's feelings are displayed- by the end of the story, it's obvious to the viewer that she isn't going to be able to live with the knowledge of what she's done. The one wrong note in an otherwise involving investigation is the mind-probe scene, which makes for distinctly uncomfortable viewing, more reminiscent of ‘24’ than any of the Upper Boat's output. Unlike Jack Bauer, however, Torchwood is not (as far as they know) resorting to torture to prevent a terrorist apocalypse, but doing so while trying to solve the murder of two burglars in South Wales. Taking such drastic measures make Jack & Co appear distinctly heavy-handed, particularly as there's no tension to distract the audience- footage of Beth with her implant active was included in last week's trailer, so we know that she'll have some sort of secret. After this sequence, I was half expecting that the proposed “stasis” would be a cover for sedating Beth and then killing her.

It’s a small aspect of the programme, but Moran deserves credit for being the first writer to come up with a truly entertaining approach to Ianto. Initially intended by Russell T Davies as being a practically non-speaking part, Chris Chibnall has been frantically trying to add depth to the butler, by giving him a nightmarish ex and a tentative relationship with Jack. However, it’s Moran’s deadpan wisecracks that make everything snap into place. The writer treats Ianto as a spectator on the team, not a member, finally making sense in narrative terms of the visible distance between this character and the other regulars. Despite already being screened in the previous episode’s trailer, the put-down response to Owen’s suggestion of an orgy had me laughing out loud. I can only hope that other writers continue this treatment of the character.

The change of tone as the Sleepers wake is unexpected and welcome, although their initial attacks have some rather odd targets. I wondered if the script was going to take a comic turn, with the Sleepers launching wrongly-targeted attacks as a result of their incomplete information (killing Cardiff City Council is not the most obvious starting point for world domination). Still, the sudden role reversal allows the episode's pace to be maintained throughout, with Torchwood chasing their opponents, instead of instigating events. And at the risk of taking this review into even shallower territory, there are some very nice explosions.

After last week’s semi-comic run-around, we’re firmly in thriller mode. That’s fair enough, but such a situation must be sufficiently solidly constructed to provide genuine tension. If you put your weight against any part of Sleeper, it wobbles. Too often, the viewer is left trying to figure out aspects of the plot, instead of being immediately aware of the action. An established trait of the Sleeper Cell is that they have personal force fields, which protect them from physical harm. Yet half their number die off-camera as a result of explosions that they themselves have caused. Jack’s exposition on the species does not mention any kamikaze strategy, so the viewer naturally assumes that all the Sleepers are still proceeding with their plan, until their deaths are casually mentioned. By not taking the time to define the limits of the enemy, the writer forces the audience to spend their time slowly reasoning out what is obviously a very flexible set of rules. Instead of cheering Jack as he runs a Sleeper over in the Mystery Machine, their thoughts are drawn to the amount of kinetic energy needed to damage the invaders. The most serious instance of this problem serves to seriously undermine the finale, as a bulletproof alien is shot dead. There isn’t actually a plot hole here- Beth had not actually succumbed to her true personality, and so would not have tried to re-activate her implant’s force field. However, the effort that it takes to figure this out is enough to draw the audience away from the moment, making the conclusion a logic puzzle rather than a moving sacrifice. The trick with sci-fi plotting is to give just enough solid facts for events to superficially make sense. Here, there are just enough to confuse.

The other major criticism that can be made concerns the characterisation of the regular team. Ianto excepted, everyone sticks to their stock roles. Jack strides about giving orders and identifying aliens, in sharp contrast to last week, where he was the spare part in his own team. Gwen makes friends with the victim of the week. Owen is selfish and bitter, ignoring the mellowing shown across the first series. Toshiko sits at her computer, with about three lines of dialogue. Moran treats the regular cast as roles, not people- all the emotion is coming from the characters he’s created. It’s all just a bit too textbook, with nothing added. A less serious niggle is the rather obvious adjusting of the script to make it easier for a pre-watershed cut to be prepared. Presumably the Sleepers’ activation orders include a command to “only cause the graphic death of your wife/child in the last four seconds of a scene”.

I want to like this episode, I really do. It's gripping and unpredictable. But too often, it’s asking me to be a script editor, not a viewer.