Transmission affords the opportunity to imagine what it would be like to board a spaceship and leave the planet, knowing you'll never return. This flight of fantasy offers something intriguing and unnerving to those of us who never would or could embark on such a journey. We, the audience, are spoken to as if we are the crew of the Saena, on the first mission to the planet Luxtaterra; the journey will take 84 years, and then it'll take a further four years for a message with the crew's findings to make it back to Earth.

It's science fiction, but is conceivably close to what could be the science facts of the future. And the first part is written and directed as the kind of polished seminar you might expect from NASA, inviting us to suspend disbelief with the aid of actors who are believable as the experts in their field.

This is billed as immersive theatre, a point I feel is arguable; the characters do speak to us through the fourth wall, but other than that we are not involved, and watch on in the same way as in any other play. The soundscape and multi-media elements work well however, with some wonderfully geeky intricate diagrams and explanations of the technical design of Saena (the space craft) and Luxtaterra (the destination). Even more of this would be even better – the detail really works, and footage would add to the immersive experience.

I thoroughly enjoyed the concept and style here, imagining being a space explorer and engaging in what might be the future in terms of interstellar travel. But the second part of the show just didn't work for me. Once the "presentation" is complete, we hear a lengthy monologue from the leader of the mission, an emotional and teary affair. This moves us away from the fascinating scientific and practical technicalities of the mission, into the psychological ones.

For the first few minutes this is fine, adding some depth – but as it extends into a long back story of the character's family, it quickly becomes tedious and out of keeping with the rest of the show. The script is trying to engage us with the struggles of her immigrant parents and grandparents; it's a tenuous link, which takes us back into the past as it attempts to draw parallels between seeking asylum and travelling to another planet. But it's not especially compelling, perhaps because it doesn't ring true that the character would give this kind of theatrically emotional monologue, and perhaps because this section's just not written all that well.

The first half is well done and gripping. There's lots of potential to expand on, as we find ourselves wanting to know more about how the mission goes and what the crew find on arrival. It's a pity that it loses its way in the second half, but Transmission is nevertheless unusual and enjoyable.