On one front, the seventh episode of Doctor Who Series 8, “Kill the Moon”, deserves a round of applause. It takes a lot of nerve to combine a family-friendly British sci-fi fable (about the Moon being the egg of a giant space creature) with strong references to the abortion debate, and yet that’s exactly what episode writer Peter Harness does. One of the reasons I always come back to the show is because it can (usually) host some of the craziest concepts without falling apart.

That’s why it’s so disappointing that the execution of this particular idea (on a number of levels) ended up being as messy and unsatisfying as it was. Too many components of “Kill the Moon” felt either rushed, lacklustre or just plain confusing. And for a television show whose batting average hasn’t been stellar lately, it’s more than a bit worrying.

As you might expect, most of the action of the episode takes place on the Moon. We find ourselves in the year 2049, when our lunar neighbour has mysteriously gained much more gravity, wreaking havoc with the tides on Earth and causing catastrophic flooding. The Doctor, Clara and her student Courtney Woods (Ellis George) rendezvous with a team of beleaguered astronauts charged with blowing up the Moon using an arsenal of nukes.

The Doctor (Peter Capaldi) believes there’s more to the story than a simple increase in gravity, and soon finds out that the Moon is, in fact, a humongous egg – which will hatch a massive creature with unknown motives. The astronauts and the TARDIS crew are left by the Doctor to make a decision on behalf of the human race, sketched out in terms of whether or not to destroy the creature before it’s born. I can almost hear the right-wing pundits firing up their blogs as I write.

As science fiction (or indeed, fiction in general) demonstrates over and over again, an intriguing concept can have all the potential in the world, only to be ruined by shoddy execution. In the case of “Kill the Moon”, it begins with the script, which grafts clunky pieces of dialogue to unwieldy exposition; it also features outbursts by Clara (Jenna Coleman) that feel completely out of character. It's especially odd when you consider some of the great work Peter Harness has done in the past, like the third series of Wallander in 2012.

It’s not clear whether Harness didn’t know how to write Clara, or whether Steven Moffatt is frog-marching the character towards a certain development, but either way, Coleman was forced to deliver some lines that didn’t fit at all with what we’ve seen from her so far. In fact, the performances as a whole in this episode seemed drained of their usual energy, including those of Capaldi and guest star Hermione Norris.

The directing and editing also suffered, with some sequences feeling slammed together for no reason, like when the Doctor pops out of the caverns below the lunar surface, or when he returns to pluck Clara, Courtney and Lundvik (Norris) out of the mining station. Later, we only get the faintest glimpse of the creature we’re supposed to care so much about, followed by another one of Clara’s mystifying tantrums, which meanders to an end once she storms out of the TARDIS.

Perhaps the central problem in “Kill the Moon” is that the episode tries to centre on a “big idea” like other works of high-concept sci-fi (the question of aborting the egg) but only spends a few minutes talking around the issue. It uses up much of the runtime with outer space visuals and red herrings like those spider monsters. Perhaps if the episode had allotted more time to Clara, Courtney and Lundvik sorting out their opinions on killing the creature, the episode would have felt more cohesive. It might have also helped build up the tension between the Doctor and Clara, so her anger would seem justified.

I’m always game to see a show like Doctor Who take on important topics, but it has to be done in a comprehensive way. Otherwise, the show is only adding more noise to a vicious debate, and depriving viewers of the fun and cleverness they expect from a Who story. “Kill the Moon” gets two stars out of four.

What did you think of the seventh episode of Series 8? Did it do justice to a complicated issue? Or were you as baffled as I was? Join the discussion in the comments section, and if you liked this review, share it with your friends and followers!