Currently, my least fav. of the Bryant and May series. I just could not follow the plot.
Now, the plots/story lines are often a bit convoluted and wander a bit, and I don't necessarily dislike them for that. I LOVE the two main characters, the frumpy Arthur Bryant, the suave John May, both elderly, but both in top-notch shape mentally. I like the staff around them; the circumstances in which they're always fighting for their special, investigative unit, the PCU, which works on crimes which might be embarrassing, sensitive, or involve highly-placed persons, etc. The locales are great, and this one, in the London subway system, or the Tube, was excellently done. (I could see, smell and hear these eerie spaces.) However...
I could JUST NOT FOLLOW what was going on with the murder(s) of various persons and those who might be involved. It was jumpy. Things poorly explained, IMO, and perhaps if I were a native or lived in or had visited London, I might have been less confused. There was a sort of 'game' here, which even though I reread certain passages, pages, etc., I just did not get.
So, for a confusing read, though delightful in places - dialogue, character, place - I had to kick it down to a low C+ or three stars. (Former teacher here; if you land in the middle you get a C.)
I look forward to the next in the series, however, as overall the series rates a solid A.
Three stars