The first two 'Messiah' series are wonderful and very nearly blameless. 'Messiah III: The Promise' is not up to the high standard set previously, but it is still a good series and definitely a worthy view.
Where "The Promise" particularly falls down is the final solution. For this reviewer it felt rushed, the killer was the most obvious of all five series of 'Messiah' whose identity was guessable too early (like the end of the first part) and despite saying before about not completely buying the motive of the killer in the first series the motive for the killer here managed to be even more far-fetched and not explored enough.
Although slightly darker than the previous two series, the tone in "The Promise" feels too different. The first two series were much grittier and more disturbing, and the downplaying of the gore here could be part of why. While admirably expanding on the previously quite limited character of Kate, and the series does a great job doing so, but it does mean that more interesting characters are too much in the background. For instance, Red is the main character but is criminally underused, feeling more like a supporting character in his own show.
On the other hand, "The Promise" is beautifully and atmospherically made, with stylish and suitably moody photography. The music has an ominous quality to it without being obvious or intrusive. The direction evokes a great atmosphere and ensures that "The Promise" never rushes or plods.
The writing is taut, tightly structured, appropriately dark and intelligent. It always flows naturally, nothing feels out of place or in bad taste and the mystery is kept alive and compelling. The story is mostly absorbing, with a good deal happening but taking care not to rush through it, instead taking its time, otherwise it would have been confusing. The story of Kate's trauma/nightmares/flashbacks are strikingly filmed, creepy and somewhat affecting, personally didn't find them tedious. Likewise the murders while not as gory or as imaginative as those in the first two series, though with a higher body count, are still inventive and harrowing.
No complaints can be made about the acting, which is uniformly good. Ken Stott is exceptional and has a riveting intensity about him, Neil Dudgeon continues to excel with 'Messiah' demonstrating some career-best work and Frances Grey does wonders with meatier material to usual.
In conclusion, worth a watch but the first two series are superior. 7/10 Bethany Cox