This audiobook, read decently by Jessica Almasy, was nonetheless not to my taste. I started in on it a bit unsure, grew to like it somewhat, and then got put off by the first person voice and the really annoying lisp these characters had who came into the story a bit later. Plus the story moved a bit too slowly for my taste.
Tapping heavily into clichés about the British, the book weaves a story about London's many underground 'rivers', which used to be above ground, but which have slowly been culverted and then covered over as London grew. They're more like rivulets than rivers, truth be told. The story premise is that these rivers are magical and dangerous if not treated carefully. Even one lone drop of water can cause havoc, which the main character learns when she gets annoyed with the fact that the water coming from the cold faucet is too cold and the water in the hot one is way too hot.
She apparently isn't smart enough to consider running them both into the sink and getting the temperature just right there, so she gets this tool from somewhere and tinkers with the plumbing until the incoming water is mixed. This of course creates a problem since the water was apparently separated for a good reason. I was driving when I was listening to this and missed a bit here and there during this sequence.
The result of her actions is that she has to tool around in the London sewerage system and recover an escaped magical drop of water. This is where the story became tedious for me and I lost interest. While your mileage may well differ, and I would hope it does, I can't commend it based on my experience, although I confess I found Jessica Almasy's accents amusing.