Ackroyd is always at his best when he is writing about London. In many of his books, London is the main character, not so much a protagonist or antagonist but a present character all the same.
This is true here.
Hawksmoor is about a series of murders that are connected with the churches in London. The book soars when dealing with London, and the menace of the neighborhood, the life of Spitalfields is wonderfully illustrated.
For all its briefness, it is a heavy book that talks a while to digest.