The third in the Kevin and Sadie series and quite different to either of the others. While I would unhesitatingly recommend them as a duo, I would be a little more cautious about this. It is not that it is a bad book, lots of it is very well observed but it depends a lot on the other books to give you investment in the characters. Kevin and Sadie struggle with the isolation of living in London, away from their communities and support networks and this struggle, combined with their combative natures can lead them to snipe at each other, making you draw on that prior investment in them. When I was first reading Harry Potter and The Chamber of Secrets I stopped reading and didn't come back to it for several years as I didn't want them to go into the Slytherin common room and get into trouble. A lot of this book felt quite like that, I would find myself silenty pleading with characters not to make one stupid decision after another. These decisions didn't come out of nowhere though, the focus (probably to a greater extent than the first two books) is on the minds of the characters and how they are thinking about things and you can see why they make the decisions you decry.
In many ways it is a credit to the series that you care so much about the characters and don't want to see them making mistakes. The book is in many ways about community, Sadie in particular is good at reaching out and making connections, with the old man whose children rarely come to see him, with the Indian couple who live in their block. It talks about the strain a lack of community can put on relationships as they become an all consuming focus and lack valves to let off frustration. It also talks about the way big cities can be lonely places with lots of people in little walled off rooms living their own lives, it made me think about how community takes a while to build and to break down those barriers, how a lack of investment in social infrastructure of communities can lead to people living less fulfilling lives. There is also the start of what feels like it will be a key theme of later books, the practical difficulties of their different religous backgrounds. If you loved the first two you will probably want to read this, and it is good, but it lacks some of the urgency and conciseness of the first two books and some of the specificity that drives that early story. That said, I particularly love Sadie's character and want to see what will hapen to them so will certainly read the later books even if it is a case of diminishing returns.
Written by Jack