BBC2/BBCHD - 30th January 2008 - 9.00pm

"I'm going to save the world in pyjamas - how daft is that?"

Ah, you see, when 'Torchwood' actually doesn't try too hard it can produce gems like this. Out goes the schoolboy gratuitous gore and innuendo and in goes sensitive, naturalistic performances, character driven storytelling and genuinely creepy atmosphere.

The danger is that the 'romance with a person from the past' is all starting to repeat itself thematically in both 'Torchwood' and 'Doctor Who'. This suffers from too much of a similarity to last year's 'TW' episode 'Out Of Time' and 'Captain Jack Harkness' and the hospital/1918 settings of 'The Empty Child' and 'Human Nature'. However, writer Helen Raynor overcomes this with a real focus on Tommy and Toshiko's developing romance. Raynor is obviously more suited to these intimate stories that don't rely on loads of effects, monsters and grandiose settings. But the other problem is that she clearly didn't know how to end this story and, whilst up to a point it is poignant and gripping, the denoument is hurried, poorly explained and undermines the drive of the narrative to that point. Owen's 'eureka' solution, to use a psychic projection fuelled by drugs to enable Tosh to convince Tommy to use the manipulator to close the rift, did not convince me and seemed a solution concocted to avoid the problems caused by sending Tosh or Jack back into the past.

And yet, this kind of development is exactly what 'Torchwood' needs right now. Sending Jack or Tosh back into the past would have bent the format out of shape rather nicely. The series relies on narratives and character arcs being resolved too tidily in 45 minutes of screen time. The series doesn't allow bigger narratives to play out and it doesn't properly measure the effects on the team of working for 'Torchwood'. There are hints here - the humanising of Owen and the tragic early deaths of previous Torchwood employees for example - but will we see the effects of this on Tosh in the next episode, or the next six episodes? We need less of the re-set button and more freedom to allow characters to reflect the devastating events they go through. They should all be basket cases by now and I want to see some of that.

Otherwise, it's pitched perfectly and played with enormous tenderness by Naoko Mori and Anthony Lewis. Naoko is given a real chance to shine here and she holds the episode together. The trajectory of the character is rather a given here but her performance is compelling and engages despite the knowledge that you know how sadly this will end. Anthony Lewis was equally good as an innocent caught up in both the machinations of the First World War and Torchwood. A captivating character with a real sense of bewilderment at what has happened to him. A doomed romance summed up by the exchange between Gwen and Jack:

'He's a soldier from 1918'
'Nobody's perfect'

That exchange gives you a sense that Jack actually knows that this is doomed but that Toshiko needs this experience. It's a bit arrogant of him but this 'need' is also reflected in that sudden eruption of passion between him and Ianto later in the episode. Human/non-human desire needs to be fulfilled and Jack seems sensitive to his team's collective drives whilst also admitting to himself that he too needs company of a kind. It also taps into the 'sacrifice of innocence' theme of the series and this episode's particular examination of the nature of heroism and cowardice.

Director Andy Goddard very effectively creates a sense of doomladen atmosphere, the sequences in the hospital were very moody with their flashing lights, rumbling and tearing sound effects. The way he created this atmosphere, through physical effects rather than computer generated ones, echoes the way 'Sapphire And Steel' also managed to sustain a sense of terror on a small budget. A more adult 'Sapphire And Steel' is the way I want the series to go and this was certainly a step in the right direction for me. Ben Foster's sympathetic score, very romantic in places, also helped to develop the 'star-crossed lovers' theme of the episode. Foster's music is coming along very nicely indeed.

This is a great episode, let down by a clumsy, amateurish resolution, but propelled by two electrifying, central performances. Refreshingly, it doesn't rely on the grubby sensationalism that afflicts much of Torchwood's attempts to be adult (compare the sensitively handled bedroom scenes between Tommy and Toshiko with the awful 'fuck fest' between Owen and Diane in 'Out Of Time'). What is clear is that with Naoko Mori, the series has got an actor capable of doing so much more than reading technobabble off screens and potentially much more it can do with Ianto and Jack, Owen and Gwen if only they're given the room to stretch. Ianto certainly needs an episode to himself to defuse the accusation that he's simply there as gay eye candy.

The best episode so far this series. Next week looks like a return to 'tabloid' Torchwood but the overdue return of Gwen's fiancee Rhys is of interest.