The third installment sees the mentally unfit DI David Creegan (Robson Green) pursuing a killer who leaves his victims in car boots with their internal organs presented in a bin bag. Anthony Matchin (a fine performance by Michael Hodgson) is the prime suspect, but Creegan knows he's isn't the killer. Internal corruption in the police force leads the OSC (Organized and Serial Crime Unit) to take over the investigation before it gets any further out of hand. (See James Hooton's riveting performance as the pathological Wayne Fitten.)
The primary problem is the storyline is composed of essentially two acts: the first half is a whodunnit which explains the plotline with such a wonderful sense of heightened intensity and meter (arguably the shows best), and the second act, more or less a whytheydunnit, which is expected to deliver the shocking climax but instead feels anti-climactic. Once the killer is revealed, I felt disappointed. It's as if the scripts resources were somewhat exhausted from the first act. Not to say the second is bad, but the drama might have been better sustained if there were three acts. The storyline could have had even more purpose should the killer not be revealed till after the final (and startling) murder.
Then the idea that Matchin becomes suicidal is a bit of a suprise. He was depressed over his wife's death, but he never displayed any real signs directly before his release from prison. With Matchin out of the picture, the trail of leads became quite singular. The murderer is someone who kills women to afflict suffering on their husbands. Someone who has a direct link between the grieving men. The identity revealed felt tame, and had it not been revealed till its latest (or a different character altogether), the lamenting could have been kept to a minimum. I can see why to an extent (no spoiler here), but with such a suspenseful first act, the opportunity to pull this episode atop in the series was left with the dead. B+