On the whole this was a well written, enjoyable, whodunit that intrigued me enough to keep me reading to the end and it's likely I'll read the next in the series.

I was slightly distracted by repetitive descriptions e.g. Nearly all women were described as having "a mop of x coloured hair" and on at least 3 separate occasions 3 different characters were hanging about like naughty schoolchildren waiting to be dismissed. Nitpicking, yes, but it was distracting. Generally the descriptive narrative was excellent, particularly in relation to the protagonist's feelings about his grandmother's illness. Some will find the detailed descriptions of the crime scenes too gruesome but I felt that the author got it just right and didn't overindulge in an attempt to shock.

The attempt to write dialogue in dialect wasn't good. It didn't read naturally at all and it seemed that having a distinguishable accent indicated a lack of social status and education, without exception. I have met very intelligent people who also have Glasweigan accents! Speaking of which, at one point, on first meeting the character, McLean is able to identify him as Glasweigan solely from hearing him utter the word "aye". Unlikely.

Overall the story is good but there were some annoying problems with the plot, not least of which was the conclusion.

Spoiler

No-one saw similarities between the first and second murders, nor the suicides. Old man dies gruesome death which involves removing a body part and shoving it in his mouth, closely followed by a suicide. Twice in a couple of days and even McLean, who felt uneasy about pinning the second murder on the boyfriend, didn't comment on the similarity until much later.

Rich people's properties are getting robbed on the day of their funeral but it never crossed McLean's mind that his gran's home would be a target, despite the security alarm being managed by the same company as the most recent robberies.

The leak being attributed to MB was way too obvious a misdirection, given McLean's involvement with Emma Baird.

The supernatural ending didn't fit at all with the tone of the rest of the book. Yes, there was a ritual murder but at no other point in the book was demonology ever entertained as anything tangible, so to end with McLean (who has a First in Psychology) suddenly becoming a believer and understanding how to vanquish this particular demon was totally unsatisfying. I like supernatural thrillers, I like subtlety, but this was out of context.

The loose ends regarding McLean's family bother me too but I assume they are meant to be tied up in the sequels,