The detective is Matthew Shardlake, a lawyer with a hunchback ordered by Thomas Cromwell to investigate the secret of Greek Fire (dark fire), which was recently discovered in England and then went mysteriously missing. Cromwell wanted the dark fire (essentially a sort of dynamite) to give to Henry VIII in the defense of England and also to save his own hide. Sharklake must crisscross London, from its courts to its seedy side, to discover what happened to the dark fire, risking his own life in the process.
I greatly enjoyed Dark Fire. I couldn't put it down and polished it off in a matter of days. Now it's a matter of returning it to my neighbours and getting them to lend me the next one!