London Bridge Is Falling Down is the most recent (2021) in Christopher Fowler’s Bryant & May/Peculiar Crimes Unit series, other than a 2022 book that appears to not be a mystery, but to rather be kind of a travelogue of London from the POVs of the characters in the series. It has dropped to $2.99 in the US.
And Fowler’s Oranges and Lemons, which is the 17th/18th in the series, depending on whether you count a collection of short stories, is going for £0.99 in the UK right now.
Buy at Kindle UK