Note: Doctor Who TV’s pre-air views aim to be as detail-free as we reasonably can while still offering a critique, but as everyone’s spoiler sensibilities are different, we advise you read on at your own discretion.

Before the first part of the big finale next week, Doctor Who indulges in one last standalone adventure this weekend.

The TARDIS lands in second century AD Scotland. Bill is determined to find out what happened to the Roman Ninth Legion, who historically vanished under mysterious circumstances. Meanwhile, the Doctor heads off and eventually runs into hostile Pictish warriors. The tribe fear for their lives, not only because of the invading Romans, but also a strange creature appears to be on the loose.

For a single episode, this one probably comes with slightly larger than average fan expectations, as it marks the first time in the revival in 2005 that a classic era writer has returned to the show. Rona Munro was previously responsible for “Survival”, the 1989 story starting Sylvester McCoy as the Doctor, and the last episode to air from the classic era.

It’s appropriate then that this episode does feel like another throwback of sorts, although unlike last week’s sixties-esque “Empress of Mars”, we could be back in the McCoy era. It’s very, very Scottish; the only thing missing is the Doctor rolling his Rs! But more crucially, it seems like Munro has settled back in right where she left off. And that might be a blessing and a curse.

There are some interesting and imaginative ideas at the episode’s core: the mythical nature of the setting, talking crows (yes, really), and a time travel plot device closer to Moffat territory. It equally shares some thematic ties with “Survival”: particularly themes of lost youth, and even the nature of the Doctor’s relationship with the Master is touched on. It looks superb throughout. The beautiful sweeping landscapes brought to life by returning director Charles Palmer (who last helmed “Oxygen”).

However, on the other side of the coin, the plot is underdeveloped in spots, and needs a bit more attention to fully flesh out some of the neat concepts. Things also get a little dull in places. It’s light on action, and just lacks a bit of energy and drive to pull you through. It’s feels like a long 45-minutes.

The titular monster itself is scarcely a part of the action too. A bit of a problem for an episode titled like this. This is no doubt due to the monster’s expensive CGI realisation. But it means it comes across as a peripheral part of the plot. It’s a shame because there’s a really interesting background behind it. A little more depth and focus would have gone a long way.

This is another story where the Doctor and Bill are split up for a decent chunk of the story. Naturally this means there isn’t much time to focus on their dynamic. Instead the Doctor and Nardole are paired up for some more back-and-forth banter. A few nice moments aside though, the main cast isn’t really given much outside of the ordinary.

Two of the guest actors have a little more of a prominent role; the leaders of the opposing sides essentially: the Roman Legion survivors led by Brian Vernel’s Lucius, and Rebecca Benson’s Pictish warrior Kar. The latter of which gives a spirited performance.

Overall, “The Eaters of Light” is an episode with a decent premise and some neat ideas, but doesn’t quite capitalise on them enough, and ends up fumbling in the dark.