The listing on imdb is inaccurate; this is actually the first story in the series. It could and should have been so much better. Even if you've never watched a police procedural you could guess that a pathologist would be present at a suspicious death. There are three such deaths in this episode and not a pathologist in sight. Needless to say none of the senior police has heard of backup. Of course the main problem is Banks; if your main protagonist is constantly dour, you need some kind of humor to relieve the mood, yet it's almost entirely absent, probably because of the deficiencies of the writer. Even Morse was occasionally susceptible to humor, and his relationship with Lewis sometimes generated sparks. Sadly in this episode the persistently insubordinate sergeant was almost invariably mouthy and unpleasant, and she should have been demoted within five minutes, as should Banks for slapping a member of the public because of something that didn't concern him.
Positives were the impressive conflagration scenes, but that's about it. The plots had potential but they were wasted because of a poor script and the miscasting of Banks.